The home secretary has announced a raft of new measures to crackdown on illegal immigrants.

Under new legislation the government is putting in place plans which could see asylum seekers electronically tagged by satellite technology within 12 to 18 months.

The measure would come into force in cases where refugee applicants could not be housed in detention centres.

Provisions contained in David Blunkett's Asylum Bill could see the children of asylum seekers who fail to return home could be taken into care.

The Department of Constitutional Affairs also outlined complementary plans to cut the amount of legal aid given to asylum seekers and reduce the number of appeals available against Home Office decisions from three stages to one.

A register of approved asylum lawyers will be established along with unique file numbers being attached to every asylum case in a bid to stop applicants from accessing poor quality advice and more than one solicitor.

Blunkett's bill has already come under heavy fire from asylum groups and the opposition.

The legislation confirmed that benefits could be withdrawn from asylum seekers who fail to return to their country of origin.

One of the most controversial elements could see the children of asylum seekers who refuse to leave being taken into care.

Whilst the policy is not contained within the legislation, it would inevitably follow on from the proposals in same way as in other cases where benefits are withdrawn from parents.

Blunkett said the moves were an attempt to make the process faster and fairer.

"The bill would introduce a new power to remove support from families who are able but unwilling to leave the UK, when they have exhausted all legal right to remain here and are refusing the offer of a voluntary, paid return home," he said.

"It is designed to encourage families to return voluntarily before their removal is enforced."

"We have to deal with failed asylum seekers who refuse to leave. I have no desire to take children from parents and put them in care unless it is an absolute last resort," he added in an article for the Guardian.

Secretary of state for constitutional affairs Lord Falconer said the legal reforms would clamp down on anyone seeking to abuse the appeals process.

"We need an asylum system that is fair and balanced both to the applicant and to the taxpayer. These reforms strike that balance," he said.

"A system that is cumbersome and time-consuming suits no-one. It creates uncertainty in the minds of applicants and leaves the taxpayer facing a growing bill.

"The current appeals system, with access to judicial review and other routes to the higher courts, creates an incentive for people to try and delay proceedings for as long as possible. The longer they can avoid a final appeal decision, the better they believe their chances of staying in the UK.

"By introducing the single-tier tribunal with one appeal, and no access to the higher courts apart from very limited circumstances, we will take a huge step towards stopping failed asylum seekers who have no chance of success from using the appeals system to delay the inevitable."

The Conservatives have already signalled their opposition to the plans - although they may find it difficult to vote against the bill as it is worded.

Party leader Michael Howard said he would instruct his MPs and peers to vote against the legislation.

"The prime minister and home secretary should be thoroughly ashamed of themselves," he said of the proposal to separate children from their parents.

Liberal Democrat home affairs spokesman Mark Oaten said the government was putting headlines before justice.

"People want a firm but fair asylum system not one that uses children as a political tool and removes rights of appeal," he said.

"These proposals show that the government is obsessed by headlines and less interested in getting the system of asylum right in the first place."

And Amnesty International UK director Kate Allen said: "The cost of Blair and Blunkett's asylum targets is being met by people fleeing torture, rape and murder in their home countries.

"Britain has a responsibility to offer protection to refugees. It is tragic that this is being eroded for short-term political gain."

The legislation came on the day that the government confirmed that the Home Office had met the prime minister's target of halving asylum applications in a year.

September's total of 4,225 applications was 52 per cent lower than in October last year.

The home secretary said the figures were a result of the crackdown on illegal entry into Britain.

"The measures the government has put in place over the last few years are bringing about a sustained improvement of the immigration and asylum system," Blunkett said.

"The number of applications has halved and is now consistently far below the levels of last year as a result of the Nationality, Immigration and Asylum Act and the historic steps to move UK border controls to France."

September's figure was up on the previous month, with the rise put down to an increase of applications from Somalians.

Blunkett said this was a "blip", but added the figure was still above those recorded in the 1990s. "We have got to get that down," he said.

Shadow home secretary David Davis said the "figures should be treated with a large amount of scepticism".

"How much of the fall can be explained by the vast increase in the number of work permits?" he asked. "How much of the fall can be explained by the government turning a blind eye to illegal immigrants?"

"The fall in the number of asylum seekers makes the home secretary's plans to take the children of asylum seekers into care seem even more unjustified."

And Lib Dem spokesman Oaten said the new figures "are misleading because they don't tell us how many individuals are arriving in the UK and decide to remain illegally without claiming asylum".