Simon Murphy blamed his decision on the fact he, like other MEPs, is forced to shuttle between the European parliament's two sites in Brussels and Strasbourg.

Whilst I understand the reasons for his decision to stand down I will not be alone in saying that his valuable contribution will be missed

Tony Blair

He branded the constant moving between sites as a "circus".

Dr Murphy, who has a young son and represents the West Midlands, said being an MEP was "incompatible with bringing up a family.

Prime Minister Tony Blair said the MEP's "valuable contribution" since 1994 would be missed.

"Whilst I understand the reasons for his decision to stand down I will not be alone in saying that his valuable contribution will be missed," said Mr Blair.

Pound 'warning'

A meeting to find a successor to Dr Murphy, who took over as leader of the Labour group two years ago, will take place next Wednesday.

MEP and former EastEnder actor Michael Cashman is strongly tipped to take over the role.

Dr Murphy will continue to represent his constituents until the next European elections in 2004.

The 40-year-old took the opportunity of his resignation announcement to call for the European Parliament to be sited in one place for the sake of its members and of taxpayers.

Dr Murphy represents the West Midlands in Europe

"My decision is a personal one, based on the incompatibility of the demands of a young family coupled with the stress of political life," he said in a statement.

"It highlights, once again, the unbearable pressures that having a Parliament with two homes puts on politicians, especially those with family commitments.

"The Strasbourg travelling circus undermines the important work MEPs do furthering Britain's interests in Europe."

Dr Murphy also argued that MEPs were hampered in exercising what he termed as their "considerable powers" when split between the two sites.

And the cost of the "continuous shuttling" cost European taxpayers' millions.

Dr Murphy took advantage of his resignation statement to warn of the dangers of the UK keeping the pound arguing that the British were in danger of losing influence.

Sitting on the bench?

"Of course we have to meet the five economic tests, but the harsh truth is that outside the Eurozone, we have little influence over many key decisions that effect the jobs and prosperity of our people," he said.

"We may be warming up for a referendum, but the game goes on without us and sitting on the bench is not cost free."

Dr Murphy pledged to play his part in delivering a 'yes' vote in a euro-referendum.

"For as long as we remain outside the single currency, we will continue to punch below our weight in Europe," he said.