Seimon Glyn's comments started the row

Mr Glyn, the chair of Gwynedd's housing committee, called for tighter controls in inward migration into Wales and referred to English as a foreign language.

Labour has previously argue that Plaid is anti-English - a charge which has been strongly rejected.

But in an article in the Welsh current affairs magazine, Barn, Lord Prys Davies, said the response of some politicians in all parties was "unfair and disappointing".

He writes: "As the flow of in-migration continues, and in what ever way we look at it - we see more and more clearly that the position and state of the Welsh language in its rural heartlands continues to decay....."

"The heartlands become weaker and rarer....this is our last opportunity to protect the Welshness of those communities where Welsh is still a social force."

Lord Prys Davies rose to prominence as the defeated Labour candidate in the 1966 Carmarthen by-election which saw Gwynfor Evans triumph for Plaid Cymru.

This is our last opportunity to protect the Welshness of those communities where Welsh is still a social force

Lord Prys Davies

The peer wanted a commission chaired by a High Court judge to examine the effects of in-migration on those areas, measure the likely threat in the future to and recommend the measures and financial resources needed to tackle these problems.

He also said it is reasonable to expect leadership from the Welsh Assembly to protect Welsh speaking communities from disappearing from the life of the world.

Plaid Cymru have welcomed what they call "this constructive and responsible reaction from a leading figure in the Labour party"

But party leader Ieuan Wyn Jones said a commission chaired by a High Court judge was not the answer.

First Minister Rhodri Morgan said while he respected Lord Prys Davies, it was better to do something practical about the problem rather than just talking about it.