A row over protecting the Welsh language in rural Wales has overshadowed attempts to set out policies to promote Welsh culture at the National Eisteddfod.

John Elfed Jones, a former chairman of the Welsh Language Board, has said that "outsiders" coming into Wales were the equivalent of "human foot and mouth disease".

Immigration from England to Welsh-speaking areas was also changing the traditional social make-up of the areas and made housing too expensive for young people, Jones said in the Welsh language current affairs magazine Barn.

"There is another foot and mouth disease which is unintentionally changing the nature of rural Wales and there is no sign either the government or the assembly is prepared to do anything to close down the devastating side effects that have been generated by this particular foot-and-mouth disease," he said.

He added: "I am referring to the in-migration of outsiders to rural Wales and the inevitable effect caused by this sort of movement. And from the mouths of these in-migrants comes the language that is familiar to everyone in rural Wales but which is a foreign language."

Leader of the Conservatives in the Welsh assembly, Nick Bourne, dismissed the comments as "deeply offensive" and warned that they would "stir up hatred".

The row follows Monday's call by Plaid Cymru for more action to help Welsh-speaking communities.

The party used the National Eisteddfod in Denbigh, north Wales, to challenge other parties to discuss the crisis in Welsh-speaking communities.

Plaid Cymru's policy director, Cynog Dafis, called for a comprehensive strategy to ensure the growth of the Welsh language, focussed on areas where the language is "a living community language".

"Recent crises, the policies of the Westminster government and long-term trends have created a serious threat both to rural and industrial communities where the Welsh language is a living community language," he said.

Plaid has faced its own difficulties with the Welsh language. Earlier in the year the party failed to discipline a councillor who referred to English immigrants as a "drain on resources".The language row is also overshadowing Rhodri Morgan's launch of Welsh Labour's consultation document on culture, sports and the Welsh language. The first minister has set out the proposals which party members will comment on as part of the process for the 2003 Assembly elections.

The measures include increased support for community organisations, more sports activities in summer schools and increased resources for adult learners of Welsh.

"This document reaffirms Labour's total commitment to enhancing the Welsh language. We are one hundred per cent behind the aspiration of a truly bilingual Wales. Realising that goal, however, will take a lot of hard work over many years. Labour urges the other parties not to abandon bilingualism in an attempt to appease extremists in their ranks," said Morgan.

Assembly e-minister, Andrew Davies has also used the Eisteddfod to describe how the internet and email could support the growth of the Welsh language.

"For many Welsh speakers there has often been a gulf between the informal Welsh that they speak and the more formal written Welsh. E-mail has already created a new outlet for informal written conversations between Welsh speakers, wherever they are in the world, and it is increasingly used as a form of communication in Welsh between young people. This is only to the good and needs to be encouraged," he said.

The Welsh Liberal Democrats launched a campaign to help rural Wales in Denbigh on Tuesday.

Mike German, leader of the Welsh Lib Dem assembly group, said the party was seeking the views of the public on measures it had helped to introduce through its role in the Welsh administration. These include an extra £60 million to be invested in rural Wales, an independent appeals mechanism for farmers and an advisory service for farmers.

German also stepped in to the language row, accusing Plaid Cymru of being "so deeply divided over this issue it renders them incapable of contributing positively towards the future development of the Welsh language."

"Whilst the nationalists remain stuck in a time warp it is up to parties like the Welsh Liberal Democrats to stand up for Welsh speakers in a constructive way," he added.