There has been a mixed reaction to Stephen Byers' decision to resign as transport secretary.

The former cabinet minister has earned praise for his development of transport policies, although Tony Blair has come under fire for not sacking the controversial minister earlier.

Byers' foe Martin Sixsmith said that the minister who had announced his "resignation" to parliament had ended up leaving the government first.

"I am officially still Stephen Byers' director of communications until next Friday," he said.

"I cannot make any comment on this matter, except to say that it is a pity it all ended like this, and if things had been done differently, the outcome could have been very different as well."

A spokesman for the Conservative party said that Byers had done years' worth of damage to Britain's transport system.

"Stephen Byers has gone but the damage he has done to our roads and railways will last for years. We have been calling for Mr Byers' resignation for months," he said.

"He has been a dreadful minister and has gravely undermined this government's reputation for telling the truth. The prime minister must take the blame for clinging onto this discredited minister for so long. However, Mr Byers' overdue departure will do nothing for our crumbling transport system.

"The real scandal of the Byers era has been the total failure of the government to implement a sensible plan for improving our railways and easing the congestion on our roads.

"The test of his successor will be whether he can get Britain moving again."

The Liberal Democrats said Byers had done the right thing.

"Stephen Byers has finally done the honourable thing - and not before time," said party leader Charles Kennedy.

"From any point of view, his position had become untenable. The prime minister must now appoint a new transport secretary who can start to put our appalling transport system right.

"Whilst this is a personal tragedy for Stephen Byers, the most important thing is not the fate of an individual minister, but giving the British people a safe and reliable transport system fit for the twenty-first century."

Lib Dem transport spokesman Don Foster added: "Stephen Byers' departure was delayed even longer than the trains over which he presided."

There was also a degree of sympathy from London mayor Ken Livingstone, who has bitterly opposed the government's plans for a London Underground public-private partnership.

"We didn't agree about the financing of London Underground but I was able to work well with him on many other issues," said Livingstone.

"Stephen Byers did not create the transport crisis after 25 years of underinvestment. He inherited it.

"The incoming transport secretary now has an opportunity to look again at the future of the London Underground," the mayor added.

SNP leader in Westminster, Alex Salmond, argued that Byers had ruined the credibility of the prime minister and the Labour Party.

"Tony Blair defended Byers at every turn, instead of sacking him long ago. And the culture of deceit and cronyism that Stephen Byers stands for runs right through New Labour," he said.

"Stephen Byers' conduct is a symptom of New Labour being one of the most deceitful political organisations in history, not the sole cause. Byers was only the monkey - Tony Blair is the organ grinder.

"Stephen Byers' behaviour - right from defending Jo Moore after her appalling email, through his serial misleading of MPs and the public - is the result of New Labour being based entirely on spin and chicanery, and throwing out any belief and principle they ever had."

Elfyn Llwyd, Plaid Cymru parliamentary leader, said that Byers had been responsible for "some of the worst decisions New Labour has made".

"Although his position became tenuous, his portfolios included many of the poisoned chalices within government departments," he said.

"We must remember that Mr Byers is responsible for the legislation that resulted in the closure of so many Welsh post offices. Although his position became tenuous, his portfolios included many of the poisoned chalices within government departments.

"Mr Byers's attitude has been typical of this New Labour government - blaming eighteen years of Tory rule instead of accepting responsibility for their own failures. It is time that this government follows his example and take responsibility for their own actions."

TUC general secretary, John Monks, said he understood the resignation decision.

"Despite his recent difficulties, Stephen's stock remains high in the trade union movement for standing up for passengers with his tough decision on Railtrack and for his record at the DTI," he said.Professor David Begg, chairman of the Commission for Integrated Transport, said: "Whoever the new transport secretary is has to accept that improving our transport network will be a long haul. The new person should given the time and opportunity to deliver it."

Anthony Smith of the Rail Passengers Council the process of change begun by Stephen Byers should continue.

"The process of change which Mr Byers started on the railways must be followed by his successor. We don't want to lose that impetus," he said.

"He made a start in dealing with the problems on the railways. He sorted out Railtrack, he found a new chairman for the Strategic Rail Authority, he kept and increased funding for the railways and he had a commitment to passengers."

"He also had the courage to set himself targets for rail performance, safety and age of trains," said Smith.

Richard Rosser, general secretary of the Transport Salaried Staffs Association, said that Byers' resignation was due to "mounting political pressure," and, "not a reflection of his stewardship of the railway industry."

"The problems the railway faces are not due to Mr Byers. They are down to previous long term under-funding and fragmentation of the network as a whole."