City Hall is preparing for the possibility of a General Election on the same day as the London mayoral vote next year.

The capital is set to elect the Mayor and London Assembly on May 7, 2020 – but with uncertainty around the date of the next national election, a clash remains possible, according to officials.

City Hall chief executive Mary Harpley, speaking at the GLA oversight committee this morning, said she was “very clear” that the prospect of a General Election next May “remains a risk”.

UK voters normally choose MPs every five years, meaning another election is not due until 2022.

But with a minority Conservative government relying on votes from the Democratic Unionist Party, and continuing parliamentary divisions over Brexit, the possibility of a snap General Election remains.

Labour assembly member Len Duvall, who chairs the GLA oversight committee, described the situation as “a disaster waiting to happen”.

Mr Duvall said counting two major votes at the same time would only “add to the complexity on the day” in the capital.

But he warned that the alternative – deferring the London-specific votes – could lead to a lower turnout in the aftermath of a General Election.

The committee chairman added that central government should foot the bill for additional costs if it held a snap election on May 7.

He said: “I don’t expect the Government to call an election and piggy-back off us to get it on the cheap. If anything it should be the other way round.”