Business leaders tonight urged both sides in the London Underground jobs dispute to resolve the row as time was running out on averting another 24-hour walkout.
Thousands of members of the Rail Maritime and Transport union (RMT) and the Transport Salaried Staffs Association are set to strike for 24 hours from 7pm on Sunday, threatening travel chaos in the capital.
Union officials had voiced hopes that last ditch talks could be held today at the conciliation service Acas, but no formal meetings went ahead.
An Acas spokesman said: "The conciliation service Acas has been in close contact with London Underground, RMT and TSSA over the past few days to establish whether there is common ground to restart formal talks. At the present time, no meetings are planned but Acas continues to be in touch with the parties and remains available to assist them if circumstances change."
Baroness (Jo) Valentine, chief executive of business group London First, said: "London Underground should leave no stone unturned, but what business really needs is for the dispute to be resolved. London's economic success and tens of thousands of jobs, not just those on the Underground, depend on keeping the capital moving."
The unions have already held one strike in protest at plans to axe 800 jobs, and will stage two more walkouts in November if the deadlock is not broken.