Irish voters should not take part in a referendum to endorse the St Andrew's agreement, the Conservative Northern Ireland spokesman has said.

Speaking in response to a Commons statement on last week's Northern Ireland devolution talks, David Lidington said Irish citizens should not have a say in the "internal governance of the United Kingdom".

Announcing details of the agreement at St Andrews, Scotland, last week the prime minister said there would have to be some form of endorsement - either an election or referendum - of the plan.

The parties in the province have until November 10 to respond to the text of the deal and, if they are accepted, devolved government could be restored by March 26 next year.

The assembly has been suspended since 2002 after an alleged IRA spy-ring was uncovered at Stormont.

Lidington said: "Whatever route the Republic of Ireland may intend to follow in this respect, it really would be constitutionally wrong for citizens of the Republic to vote in a referendum on a matter that related solely to the internal governance of the United Kingdom, and that a referendum in the Irish Republic should surely be confined to changes in that country's constitution or system of government."

Northern Ireland secretary Peter Hain replied: "The different parties are thinking about this and plan to come back to us on this and we'll really await the outcome of their deliberations."

In his opening statement to the Commons, Hain said: "In March the electorate will have the opportunity to endorse the St Andrews Agreement either through an election in Northern Ireland or through a referendum.

"We will listen to the views of all the parties before making a decision on the most appropriate way of consulting the electorate and legislating accordingly."

He said the agreement could come to be seen as a "pivotal moment in history", paving the way for a "new dawn for democracy in Northern Ireland".

And he said if the parties did not go ahead with the agreement, the assembly would be dissolved.

"There is not a choice between St Andrews and something else; there is only a choice between St Andrews and dissolution," he said.

"Friday 13 October was a good day for Northern Ireland. It has the potential to be greater still, to be the foundation stone of a new Northern Ireland, based exclusively on the principles of peace, justice, democracy and equality.

"Whatever the difficulties that lie ahead, I trust that none of those who took part in the talks at St Andrews last week will lose sight of that great prize."