London mayor Ken Livingstone has said London Underground maintenance firm Tube Lines has "no reason" to axe hundreds of cleaners' jobs.
Tube Lines is investing in "innovative" cleaning strategies
The Rail Maritime and Transport (RMT) union has warned nearly 200 workers employed by Tube Lines contractor ISS face being laid off.
Tube Lines said it was "refocusing resources" for station cleaning.
But Mr Livingstone said the company was enjoying profits and could not justify the planned cuts.
On Thursday, RMT general secretary Bob Crow said workers were "stunned and furious" when they were told their jobs may be axed.
Mr Livingstone said Tube Line's contract made it responsible for cleanliness on the Tube.
He said: "I do not see how they can maintain standards of cleanliness by cutting staff.
"Given the profits that the infrastructure companies enjoy, there is no case for reducing these cleaning posts."
Earlier Mr Crow said: "There is no way that levels of station and train cleanliness can be maintained on the Jubilee, Northern and Piccadilly lines with a loss of 27% of the cleaning workforce."
The union said the job cuts would raise "serious safety and security issues" as free newspapers were swamping stations and trains everyday.
A Tube Lines spokesman said: "We are continuing to invest in innovative solutions to improve ambience, such as anti-graffiti film.
"Through improved standards, better management and investment in cleaning tools, we believe we can now refocus our resources in terms of station cleaning."