London's transport commissioner Bob Kiley has begun the first stage of his legal action against the government over privatising the Tube.

Kiley went to the high court on Thursday after negotiations ended in deadlock last week with the government refusing to hand him the concession of controlling the daily management of the system.

An initial hearing has been scheduled for April 23 ready for a likely start on April 30.

Kiley said on Sunday that he was still hopeful the deadlock could be broken even at this late hour, telling the Frost programme: "As far as I am concerned the door is never closed on talks."

Government officials have begun a final round of talks with PPP bidders to find out what concessions they would be prepared to allow Kiley.

The delaying of the general election has effectively won the government valuable time to hammer out the deal that has so far failed to materialise. If the officials fail then they face the embarrassing prospect of a high-profile court case starting just days ahead of the general election campaign.

Also on Monday, Ken Livingstone started a lobbying campaign of the capital's business leaders and councillors, blaming "misguided intransigence" by the government for the crisis.

The London mayor hopes that his initiative will embarrass the government into returning to negotiations.

Livingstone again outlined his final position saying that he was prepared to accept the financial constraints of a PPP deal but he would not accept safety issues being compromised.

Senior City figure Lord Sheppard, who is also chairman of London First, told the FT that the government should accept the fact that Bob Kiley "will have to operate the Tube once new PPP arrangements are in place and it would be untenable to proceed if he is not convinced they are safe and workable".

He said that the Underground should be handed over to Transport for London with adequate funding for maintenance work if negotiations were delayed any further.

The Conservative transport spokesman Bernard Jenkin said the government "should stop playing politics with this. The next Conservative government will do business with Mr Kiley, which is what Labour should have done months ago".