Talks are to be held in a bid to avert a strike by thousands of London Underground workers in the new year over job cuts and ticket office closures.
Members of the Rail, Maritime and Transport union and the Transport Salaried Staffs Association are due to walk out for 24 hours from the evening of January 8.
The conciliation service Acas will host talks today between London Underground and the two unions, whose members have been banning overtime.
TSSA general secretary Manuel Cortes said: "We are hopeful that talks will finally lay the groundwork for a return to proper staffing levels.
"Tube passengers are feeling the effects of our overtime ban which has closed many stations because London Underground are simply not employing enough people to keep the Tube open.
"After nine months of this chronic understaffing, our members are not just worn out trying to make up for the shortfall in staff, they're angry that their bosses aren't sticking up for a properly staffed Tube able to provide a safe service for passengers.
"London Mayor Sadiq Khan's new administration was decent enough to order their own review of the impact of closing ticket offices and it concluded new 'customer focal points' on stations are needed.
"We need to reopen them, get the staffing back up to legally safe levels and get the new year started with the good news of a big staff recruitment programme that can return decent customer service and proper safety and staffing levels to our Underground."