Paul Murphy was the first Welsh secretary after devolution

Mike German says he fears that Mr Murphy arrives with "baggage" over his attitude to devolution and will hamper further transfers of legislation.

"I think things can only get worse, as matters are held up," warned Mr German.

But Mr Murphy insisted that one of his priorities was to improve relationships between the assembly and Westminster.

Following the resignation of Peter Hain, who quit after his deputy leadership campaign donations were referred to the police, Mr Murphy returns to the position he held for three years.

'Veto'

Mr Murphy told BBC Radio Wales that he wanted the constitutional relationship between the Welsh Assembly Government. the assembly and parliament to work "smoothly".

"I think the priority for me really is to ensure that we understand each other in our respective roles, and to perhaps improve the relationship," added Mr Murphy.

"Over the last number of months it has been a bit rocky for all sorts of reasons and I think that's already started to happen under Peter [Hain] and I hope to continue that."

But Mr German said he feared that Mr Murphy came to the post with his own political agenda.

PAUL MURPHY FACTFILE Born 25 November, 1948 Lecturer in history and govt, Ebbw Vale College, 1971-87 Torfaen councillor 1973-87 MP for Torfaen from 1987 Shadow spokesman for Wales 1988-94, Northern Ireland 1994, foreign affairs 1994-95, defence 1995-97 Northern Ireland minister 1997-99 Welsh secretary 1999-02 Northern Ireland secretary 2002-05 Murphy returns as Welsh secretary

"The problem is he comes with a little bit of baggage here about his attitude towards devolution and the transfer of powers," warned Mr German.

"The Prime Minister has handed this man a veto, an absolute veto, over passing powers on to the national assembly. I think we are in for a bit of a sticky time."

Mr Murphy admits he had never been an "enthusiast" for devolution, and opposed the coalition between Labour and Plaid Cymru to form the assembly government last summer.

But he said his party had made a democratic decision, which he must work with.

"My job is to ensure that...we get decent services, that the relationship between Cardiff and Westminster is constantly improving.

"And that the new constitutional settlement, that's to say the way laws are made up here and in Cardiff, that it works smoothly."

He said the position of Welsh secretary was "very dear to my heart as a Welsh MP" and there was a "very big job to be done".

The presiding officer of the assembly, Lord Dafydd Elis Thomas, has described the concerns raised by the Welsh Lib Dem leader as "total fantasy".

Lord Elis Thomas added: "Paul Murphy's views, or my views, are not the issue here. The issue is making the constitution of Wales work - and Paul will do that."