Former Welsh Secretary Ron Davies has been branded "treacherous and untrustworthy" by a fellow Labour MP for calling for further powers for the Assembly.

Jackie Lawrence - who is Secretary of the Welsh Parliamentary Labour Party - also said he should join Plaid Cymru.

Ms Lawrence made her strong attack following a newspaper report that Mr Davies would call for extra powers for the Assembly in a speech this week.

His comments follow criticisms he made last week of the handling of top-level European funding by the Labour Assembly cabinet.

The speech is likely to increase speculation that a no-confidence motion in Alun Michael next month will lead to a coalition running the Assembly.

"Ron is out on a nationalist limb and is seen increasingly by his Labour colleagues as treacherous and untrustworthy,"said Ms Lawrence.

"In view of his nationalist leanings, Ron would be as well to take up Dafydd Wigley's offer rather than whinge on the Labour benches where he has no support for his increasingly extreme views."

The Labour MP for Preseli in Pembrokeshire called his suggestion that the Assembly's powers be increased "sheer nonsense".

Press reports have said that in a speech to be delivered at Cardiff University on Wednesday, Mr Davies will accuse Labour of being anti-devolution.

He also plans to call for a Speaker's conference under Assembly Presiding Officer Dafydd Elis-Thomas to examine proposals to increase the powers of the National Assembly for Wales.

"If the quotes in the Press are correct, he has either lost his own plot or he appears to have deceived the Welsh public into his real agenda for the Assembly," said Ms Lawrence in a statement.

'President of an independent Wales'

"It seems that his real ambition is to be president of an independent Wales rather than leader of the Assembly.

"That is something he would not achieve under a Labour banner.

"The Assembly has a massive job to do to cope with its existing workload. Neither Ron himself nor Plaid Cymru have done anything positive in the past six months to get that job underway.

"The Assembly needs to use its existing powers to the full. Any talk of extending powers is premature."

'Nothing wrong in debate'

But Mr Davies said he was trying to extend debate in a bid to improve the Assembly.

"Surely nobody is suggesting that we can never examine our democratic institutions with a view to improving them," he said.

"If there's a consensus that the powers of the Assembly should be extended, I see nothing wrong in debating that.

The Caerphilly MP denied he wants to be "president of an independent Wales".

"I have no desire to be president of anything. I certainly don't want to see an independent Wales and I certainly have no desire to leave the Labour Party - of which I've been a member for 30 years."