The home secretary has defended his controversial plans for further reform of the asylum system.

David Blunkett told MPs on Wednesday his plans would tackle organised criminal gangs exploiting vulnerable people and migrants trying to subvert the asylum system.

He told the Commons, during the second reading of the government's Asylum and Immigration Bill, that changes were vital.

Removing people who had destroyed their documents was now a major problem as this meant officials could not determine which country they had come from.

Blunkett claimed these people were "determined to make a monkey of the system".

"This is a real crunch issue because 70 per cent of applicants have either never had or thrown away their documents," he told MPs.

"We have the devil's only job at the moment to actually be able to target that. Without a country to receive them, we've nowhere to send them. We can't send them into outer space."

The home secretary claimed "unprecedented" people movements had created massive problems for officials.

"The massive increase over the last three years in particular did undoubtedly put pressure on the system," said Blunkett.

Proposals to remove all benefits from failed asylum seeker families, forcing the authorities in some cases to take children into care, have already come in for heavy criticism from refugee groups and opposition parties.

The Conservatives branded the bill "despicable" when details emerged before last month's Queen's Speech .

The party's home office spokesman Humfrey Malins said the government's second Bill in two years was a sign of failure.

"We legislate too often and too hastily," he said. "There is a growing feeling that the government is beginning to lose control of our borders.

"There is a lot in this bill to which I do not agree with and must be tidied up; either in committee or in the Lords."

He gave particular anger to the response from ministers to the issue.

"It begins to look not just inhumane but inefficient."

Blunkett wants to introduce electronic tagging for people waiting to be deported from Britain and plans reduce the number of appeals and level of legal aid available to asylum applicants.

And the Bill contains measures to crack down on the 70 per cent of asylum seekers who claim to have no documentation on arrival.

Ahead of the second reading of the bill on Wednesday, Blunkett told the BBC that the proposals were fair to both applicants and the public.

"Do we carry on paying these people and housing them ad infinitum, because if we do we have no effective measure other than forcible removal," he said.

"As we can't re-document some of these people, because they won't co-operate, we can't forcibly remove them to their country of origin because the country won't take them.

"I need to ensure that people feel safe, that they are not egged on by those who would use insecurity and instability and difference as a method of whipping up racism and xenophobia.

"People want to be able to welcome people legally into this country to come and work here and visit their families here, and they will only accept that if they know we have got a grip on clandestine entry and working and those who abuse our hospitality."

Home affairs select committee chairman John Denham said the government needed to ensure Blunkett's principles worked in practice.

"In many cases the bill has got the principles absolutely right," he said. "What parliament has to look at is how it will work in practice.

"Simplifying the appeal system, so that people can't have an endless series of appeals to delay a final decision, is a good idea in principle.

"But the government has got to show us that they can improve the quality of the initial decisions that are taken."

The former Home Office minister added that his old boss was right to withdraw benefits, but should be careful about the impact on children

"It is very difficult to say to taxpayers in this country that if a family have no right to be here, just carry on being supported by the taxpayer," he said.

"The emphasis has got to be on returning those people to their country of origin wherever possible.

"The principle of withdrawing benefit is right, but the worst possible outcome would be if you ended up with children in care, and parents staying on illegally in this country.

"What we need to press the government on is how they are going to back this measure up, with much more supportive measures to advise and support families to take the opportunity which is there to go back.

"It's a very tough measure and that's why the government has got to show that they can operate it humanely."

And former immigration minister Barbara Roche has performed a policy u-turn by calling for initial decisions on asylum cases to be taken completely out of the hands of the Home Office.

The job should be given to an independent refugee board.

She said the move would increase confidence in decisions and cut the 20 per cent of cases which are currently overturned on appeal.

"The whole issue is getting the decision right in the first place," the MP said.

"In the long term, we ought to look at whether, when we make initial decisions, we can make them in a totally independent way, independent of the Home Office.

"If we did that, we would get a much speedier process and people would know their position at a much earlier stage.

"I have no doubt of the integrity of the men and women who make the initial asylum decisions, but having that independence at an early stage would restore confidence in the decision."

Liberal Democrat home affairs spokesman Mark Oaten said that Blunkett's legislation went against "natural justice".

"The idea that to tackle immigration, you take away levels of natural justice by removing the level of appeal and that you start having a media game by using children as a threat to remove asylum seekers, I think is a step too far,'' he said.

"They are removing benefits from families with children and they have said that a consequence of that may very well be that children need to go into care. I think that is wrong.

"The home secretary currently has the power to arrest and remove these people.

"He should use that power. Instead, what they seem to want to do is remove benefits and use children as a threat."

And a coalition of refugee and human rights organisations said the bill would send asylum seekers back to face torture, persecution or death in their home countries.

Amnesty International UK director Kate Allen said it would be "devastating".

"When initial decision-making is so poor, the appeals process can be the only barrier between a refugee and the secret police waiting to torture them on their return," she warned.

Refugee Council chief executive Maeve Sherlock said "the effect of these measures plus the proposed restrictions on legal aid would deny a fair hearing to asylum seekers".

"Getting asylum decisions right first time will lead to fewer appeals, speedier results, lower costs and greater public confidence in the system," she said.

And Refugee Legal Centre chief executive Barry Stoyle said "the appeals system is being watered down".

"The proposed one-stop appeal tribunal will be unaccountable before any law court, reviewing its own decisions," he claimed.

"The tribunal will make life-or-death decisions without anyone being able to question them."