Millions of commuters will have to wait until next week to find out if a strike by Tube workers is going ahead.
Union leaders will meet on Monday to decide whether to press ahead with two 24-hour strikes on London Underground from Tuesday and Thursday evenings.
The Rail, Maritime and Transport union (RMT) is in dispute over plans for a new all-night Tube service from next month.
Unite and the TSSA union are also planning to strike, but the drivers' union Aslef will not be joining any action next week. Talks aimed at resolving the dispute will resume at the conciliation service Acas today.
The RMT said a full report on the outcome of many hours of intensive negotiations will be taken back to the union's executive on Monday.
Acas said talks with the parties involved in the London Underground dispute have adjourned and will resume on Monday.