Brighton and Hove Council leader Lynette Gwyn-Jones is quitting her post after only 18 months.

The Labour boss of the council made the announcement during a speech at the budget meeting last night.

She succeeded Lord Bassam after he became a junior Home Office Minister, winning the leadership by one vote over Councillor Ken Bodfish.

Coun Gwyn-Jones will stand down when her term of office ends early next month. The ruling Labour group will then choose a successor. Coun Bodfish is clear favourite.

She said: "I am concerned for the interests of the council, my colleagues and above all the electorate and will do all in my power during the remainder of my period of office to ensure we have a smooth and effectively-managed transition.

"I hope by announcing this today I will enable us all to cease the orgy of speculation and get on with our proper business.

I feel this is perhaps an unexpected but, I think, appropriate moment to do this.

"This is not a farewell speech and I am certainly not announcing my departure from public life.

"I intend to fulfil my duties in the interest of the authority to manage the change to a new leader. So a final farewell is for another time."

Coun Gwyn-Jones outlined achievements during her time of office including improvements in education and more money spent on social care and health.

She also pointed to real progress made on developing sites such as Brighton station, Shoreham Harbour and Jubilee Street.

But during her term, the leadership lost crucial council votes including two on the future shape of the council, one just two weeks ago.

On Tuesday this week it had to concede defeat and postpone a referendum on having a directly-elected mayor until October instead of holding it in May.

The leadership was also defeated over whether Brighton and Hove should call for a public inquiry into a child abuse case while a Tory proposal for new council wards was chosen by the Local Government Commission instead of Labour's.

Opposition Tory leader Geoffrey Theobald commented: "I expected this to happen but not necessarily now. Tony Blair will shortly be leaving office in exactly the same way.

"This is a bitter blow for the Labour group. Our decisive victories on a number of issues have engineered this defeat. They are in turmoil."

Coun Bodfish, a former Labour leader on East Sussex County Council and a member of the ruling Cabinet, is certain to stand in the new contest.

There is a possibility he will be elected unopposed. His Cabinet colleague Ian Duncan said: "I do not intend to stand although I would like to play a part in the administration."

At present there is no sign of a challenge from the Left, whose contender last time was Francis Tonks.