London mayor Ken Livingstone has dropped his High Court action over PPP Tube deals.

The decision was announced on Friday morning.

The mayor had been suing London Underground for the right to see key documents related to contracts for private companies to run part of the Tube.

He had argued that the arrangements for PPP violated European funding and procurement rules.

Livingstone's lawyer Lord Lester of Herne Hill QC, told the court that the mayor and his transport chief Bob Kiley were withdrawing their case "as responsible public servants and authorities" because they did not think they would get the orders they were seeking.

"During the course of the hearing, it has become clear that some or all of these procedural objections are likely to be accepted by your Lordship," he told the court.

"The claimants have therefore been advised that they have no reasonable prospect of obtaining an effective remedy for the breaches of the procurement rules they have raised in these proceedings and which remain of grave concern to them."

London Underground's chief Paul Godier described the move as "the right decision for London".

"Let us all now hope that we can get on with finalising the contracts without any further legal argument or unnecessary delay. What really matters now is getting on with the long overdue task of fixing the Tube."

Tube unions said the wider issue of the PPP deals was still a matter of concern irrespective of the court case collapse.

Mick Rix, general secretary of the train drivers union Aslef, said: "We still hope that Alistair Darling will have a rethink on PPP because irrespective of legal technicalities it is a scheme that will be a disaster for the travelling public and the taxpayer alike."