London taxpayers could face an additional £2.5 million burden if West Ham United are relegated from the Premier League this season due to the club’s lease agreement for the London Stadium.

West Ham sit 18th in the league table with one match left to play and risk dropping to the Championship if Tottenham Hotspur, who are two points ahead with a game in hand and a superior goal difference, avoid defeat against Chelsea FC on Tuesday.

Under the terms of West Ham’s 99-year lease at London Stadium, the club’s annual rent would fall from £4.4 million to about half that amount if they are relegated.

The reduction would leave the Greater London Authority facing a funding shortfall, with taxpayers expected to cover part of the stadium’s operating costs, including stewarding and maintenance expenses.

Speaking to BBC Sport, Sadiq Khan said relegation would have financial consequences for the city.

“If West Ham are relegated, we, the taxpayers, we City Hall, could lose up to £2.5 million a year,” Khan said.

He added: “So what I say to Londoners who don’t support Spurs is you should probably be cheering on West Ham, because the taxpayer will lose out if West Ham go down.”

Khan also criticised his predecessor, Boris Johnson, accusing him of agreeing to “the worst deal imaginable” when the lease arrangement was approved in 2012.

Commercial revenue generated by the stadium is also expected to decline if West Ham are relegated, while operational costs could increase due to a longer Championship season involving 23 home matches compared to 19 in the Premier League.