Alan Howarth has previously been loyal

They said debate about the euro deflected attention away from the NHS, schools and other sectors of the economy such as manufacturing.

The letter published by The Guardian newspaper on Tuesday urged the Government to concentrate on "the real priorities for Britain".

The signatories also include the Blaenau Gwent MP Llew Smith and Denzil Davies, the member for Llanelli, west Wales.

Their comments coincided with the launch of the Labour Movement for Europe, a network of MPs who will campaign for Britain to join the single currency.

Loyal defector

Alan Howarth is a former Conservative MP for Stratford-upon-Avon and junior minister who defected to Labour before the 1997 general election.

He was selected to fight Newport East in place of the retiring member Roy Hughes amid accusations that he had been "parachuted" into the safe seat.

Newport East includes Llanwern steelworks

Now known as Lord Islwyn, Mr Hughes later revealed that he had asked for a peerage shortly before stepping down from the Commons.

Mr Howarth served as Labour's Minister for the Arts until the 2001 general election.

His intervention is significant in view of his previous loyalty to the Labour Government.

The Newport East constituency he represents includes the giant Llanwern steelworks which closed last year with the loss of more than 1,300 jobs.

A poll published by BBC Wales earlier this month suggested a narrrow majority of people in Wales supported signing up to the euro.

Europe Minister Peter Hain welcomed the NOP survey claiming it showed the tide was turning following a series of UK-wide polls which indicated a majority against joining up.