Tube unions will push for a pay rise in each year of any deal week

Meetings will be held with officials from the Rail Maritime and Transport union (RMT) and Aslef.

Union leaders warned that time was running out on Ken Livingstone's hopes for a four-year deal to avoid what has become an annual row.

The unions will push for a substantial rise in each year of any deal week and a cut in the working week.

Mr Livingstone said last year the annual battle over pay was "nonsense" and promised hard negotiations to try to achieve a groundbreaking agreement.

A London Underground spokesman said: "London Underground will enter detailed negotiations with the unions later this week towards a long-term pay and conditions deal or stability agreement.

"The agreement could cover a period of up to four years. We hope such an agreement could end the annual cycle of pay claims and the resulting threat of strike action of the Tube.

"We expect these to be long and challenging negotiations but we are committed to working with the unions."