THE Northern Ireland peace process was thrown into uncertainty yesterday when Gerry Adams, Sinn Fein president, warned of a return to violence and rejected further exploratory talks with ministers.

Speaking from South Africa where he is to meet President Mandela tomorrow, he insisted: "As far as Sinn Fein is concerned, the exploratory talks have finished."

Michael Ancram, political development minister at the Northern Ireland Office, last night refused to comment on Mr Adams' claim that there is "a crisis building up" because the Government will not engage in all-party talks involving Sinn Fein. Ministers are to study a full transcript of the Adams remarks, made in an interview for BBC Radio Ulster's Inside Politics programme, before responding to the latest disturbing twist in the peace process.

Irish government officials said Dublin was anxious to see the momentum of the peace process maintained. "The arms issue should not completely take over. It must not be allowed to derail the process. It is an important element but there must be progress on a variety of fronts. We are anxious to see moves towards talks."

Mr Ancram has held two rounds of exploratory talks with Sinn Fein officials, but Patrick Mayhew, the Northern Ireland Secretary, has refused to go beyond the brief get-together he had in Washington with Mr Adams until there is movement on the decommissioning of IRA weapons.

But the Sinn Fein president argued that the IRA will not get rid of its weapons until there is substantial progress in the political process. The IRA's "big contribution" had been to call the ceasefire last year.

Mr Adams blamed the Government for problems with the peace process, adding: "Of course we wish to meet ministers; we wish to make representations on a number of issues, but we are also very mindful that we don't get stuck into talks which have no purpose whatsoever other than to be stalling the process.

"If Patrick Mayhew and John Major are genuine about recognising the rights of Sinn Fein voters then it should be simply a matter of arranging diaries."

Mr Adams warned that if there could not be talks, then there could not be any settlement. "An obstacle is being placed in the road to a settlement," he said. If the Government would not start all-party talks, then the parties could not get together to make the agreement that would finally make peace.

"We have not yet got peace. We can only get peace by agreement, by dialogue and by removing the causes of conflict, and if you don't remove the causes of conflict then the source of conflict remains."

Mr Adams said: "There is always a danger, unless we deal with the root causes of conflict, that the danger of slipping back into conflict remains, and Patrick Mayhew and John Major know that."

There was "widespread concern" in the republican movement and beyond about the Government's "failure to grasp this historic opportunity with the sincerity and with the urgency it deserves". The Government needed to simply set a date on which the British and Irish governments would "lead all of the parties into all-party talks to seek agreement, to get agreement to build a lasting peace," Adams said.

Dublin officials said the Unionists, who have insisted that the IRA's weapons be decommissioned before they will enter all-party talks, are privately calm about Mr Adams' warnings, regarding them as part of the power-play of the peace process. A resumption of the IRA's shooting war is not regarded as imminent.