Mr Adams, who denied a report that he planned to apply for a visa to visit the United States after his controversial 24-hour trip last February, attacked both the British and Irish governments.
His remarks were made against a background of continuing violence. The body of a woman was found on the Co Fermanagh border with the Irish Republic after an IRA claim that it had 'executed' an informer.
A national delegate conference of Sinn Fein is expected to be held in the Irish Republic next weekend to discuss the final response to the Downing Street declaration.
Last night, in a statement issued in Belfast, the Sinn Fein president said any future negotiations on the constitutional issue must be aimed at bringing about a 'just and lasting settlement'.
'A solution, a negotiated settlement, requires constitutional as well as political change,' he said.
'Cosmetic or semantical change in either the Government of Ireland Act or the Irish Constitution will serve only to invite reaction, without bringing about the new beginning that is so obviously required in this situation.'
It had taken a long time to create conditions in which the Government of Ireland Act could be on the table for negotiation. 'It is of crucial importance that this opportunity is not squandered,' Mr Adams said. 'Sinn Fein has consistently argued that the consent and the allegiance of Unionists is needed to secure a peace settlement. However, the Unionists cannot have a veto over British policy and the British government must stop hiding behind the pretence that they do.'
An investigation began yesterday into a disturbance at Crumlin Road prison in Belfast on Saturday night involving up to 100 prisoners. The disturbance followed a rooftop protest nine days earlier by loyalists protesting against overcrowding.