A vital by-election will be held in Brighton and Hove following the death of a councillor.

The ruling Labour group in the city faces losing its grip on power if the party fails to retain the seat.

The by-election has been called after the sudden death of Labour's Gerry Kielty, who held the ward with a slim 80-vote majority.

Labour runs the council, despite having 24 councillors, fewer than half the city's total.

The Conservatives have 20, the Green Party six, the Liberal Democrats three, with one Independent.

If the Tories snatch the Hangleton and Knoll ward, they could form an alliance with the Lib Dems and take control.

Green Party leader Councillor Keith Taylor vowed to block any such grouping, as well as ruling out a blue-green coalition taking power.

Councillor Sue John, deputy leader of the Labour group and the council, said she was confident the seat would be held.

She said: "This is a natural Labour seat and I am looking forward to a positive result.

"We do expect to do some work and we are not complacent but we have an extremely good record in the ward.

"This is not making us lose sleep at the moment - I'm going to keep that seat for Labour and that's what Councillor Kielty would have wanted."

Coun John said more than £5 million had been spent on schools in the ward since 1997 and parents would have seen improvements.

Councillor Ann Norman, deputy leader of the Conservatives, said: "We will fight a strong election campaign and will go all out to win the seat. This election could change the political balance of the council.

"By-elections often bring about surprise results and Hangleton and Knoll does have a good representation of Conservative voters."

Asked about an alliance with one of the smaller opposition groups, she said: "We are not ruling it in but we are not ruling it out."

Coun Taylor said: "We did not form an alliance to take control with Labour because we did not want to be held responsible for their mistakes.

"Knowing the Tory party as we do, there is absolutely no way we would want to be in an alliance with them."

He confirmed the Greens would try to stop a Conservative and Lib Dem leadership, saying "it would not be in the interest of the city."

Lib Dem leader Councillor Paul Elgood refused to rule out forming a new leadership with the Conservatives if the party won the seat.