Mr Khan said: “The only reason we increased fares by RPI+1 [this year] was as a condition of us receiving funding from the government as required because Londoners did the right thing.
“Judge me on my record, in my first five years as mayor when the government wasn’t seeking to micromanage TfL we froze fares.
“My concern actually is what happens this September when inflation could be at 8% to 9%.
“And if the government requires us next year to do another RPI+1 [inflation] that’s a 9% to 10% fare increase for the poorest Londoners that you and I really do both care about.
“It’s really important the govt gives us a decent deal both in terms of operational support this year and also long term capital going forward.”
This would mean a bus fare might go up from £1.65 to £1.80 (9%) and a Zone 1 peak journey could go up from £2.50 to £2.75 (10%).
Green Party assembly member Sian Berry commented: “The rate of inflation is terrifying when you think about what that might do to fares.”
And the mayor added: “Londoners are currently facing three big issues - energy, National Insurance and inflation. I don’t want to add to that with an increase in fares next January.
“If fares are more affordable, more people use public transport. There’s an economic case to keeping fares low, and a moral case of supporting Londoners during this crisis.”
A Department for Transport spokesperson said: “We have repeatedly shown our commitment to supporting London’s transport network throughout the pandemic, providing close to £5bn in emergency funding to Transport for London - all at a time of significant pressure on the national finances.
“Decisions on TfL fares are a matter for the Mayor and he must take responsibility.”