Northern Secretary John Reid is to have talks with Sinn Fein on Thursday over their complaint that he is taking a pro-unionist stance.
The party has accused Dr Reid of seeking to consolidate David Trimble's position as UUP leader since replacing Peter Mandelson.
Sinn Fein President Gerry Adams said Dr Reid had also backed Mr Trimble in the row over the First Minister's refusal to nominate Sinn Fein ministers to North-South meetings.
However, Dr Reid has rejected the allegations, saying that he never argued that decommissioning was a pre-condition for anything.
He said that the British government had begun reforming the RUC despite the lack of any handing over of arms.