Language activists staged a six-hour blockade of Welsh government offices yesterday to demand First Minister Carwyn Jones act over the "crisis" in numbers of Welsh speakers.

Six members of Cymdeithas yr Iaith Gymraeg (the Welsh Language Society) swooped on the government's Llandudno offices at 6am, chaining themselves to the main gates.

Cymdeithas chairman Robin Farrar, who led the protest, said: "There's a real crisis facing the language, but the Welsh government is not acting seriously.

"We're certain that our unique national language can thrive over the years to come with positive campaigning and political will.

"But, instead of changing policies and introducing new ones, we have seen more of the same from Carwyn Jones and his government."

Five hundred workers were locked out of the offices for hours by the protest, which the group ended voluntarily shortly after midday.

North Wales Police monitored what they described as a "peaceful protest" and arrested one local man, who was not part of the protest, for breach of the peace.

The blockade marks the start of a campaign of civil disobedience to demand measures to reverse the declining number of Welsh speakers revealed in last year's census results.

The number of people able to speak Welsh fell by 1.3 per cent between 2001 and 2011 and it became the minority language in its Carmarthenshire and Ceredigion heartlands.

Mr Farrar accused Mr Jones's Welsh government of a "lazy" response.

"We don't trust the government and a number of top officials to prioritise getting to grips with the factors like planning and education which threaten the longevity of the language," he said.

A Welsh government spokeswoman hit back, saying she was "disappointed" by the protest, especially since officials had held "regular, and constructive, dialogue with the group."

She said: "Over the past year we have taken positive action to promote the Welsh language, including significant measures such as publishing proposed standards to improve Welsh language services to citizens."

But Mr Farrar promised more direct action after "endless" conversation with the Welsh government had produced no action.