LONDON (Reuters) - London commuters face more travel chaos in February and March as underground train staff press their case over staffing levels with another round of strikes.

British Airways “mixed fleet” cabin crew, who make up around 15 percent of total BA cabin staff, also plan to stage more strikes next month in a pay dispute.

The RMT union said staff working on the “Tube”, as the world’s oldest underground rail network is known, would stage a 16-hour walkout from 6 p.m. (1800 GMT) on Sunday Feb. 5 and again for 15 hours on Tuesday Feb. 7. from 10 a.m.

More strikes are planned for March.

A 24-hour walkout on Jan. 9 caused most stations in central London to close, including those serving London’s mainline stations such as Victoria, Kings Cross and Waterloo.

The action comes after talks failed to resolve a dispute over staffing levels after the closure of ticket offices in recent years.

“RMT will not stand by while safety is compromised on London Underground off the back of cash-led cuts to staffing levels that the union has warned would have a serious, lasting and corrosive impact for staff and passengers alike,” said the union’s General Secretary Mick Cash.

Transport for London (TfL) has said it agrees more staff are needed in stations, and that it had already started recruiting extra workers. London Mayor Sadiq Khan has called the action totally unnecessary.

This month’s action led to huge queues for buses in central London while many major roads in the city were gridlocked.

Separately, the Unite union announced that mixed fleet cabin crew working for British Airways, owned by International Airlines Group, would stage six more days of strikes, from Feb. 5 to 7 and Feb. 9 to 11.

During previous such strikes, the airline has said all its passengers would be flown to their destinations and only a small number of short-haul flights would be canceled.