Northern Ireland's First Minister, Mr David Trimble, has warned that the Patten report on the RUC's future, due to be published on Thursday, could derail Mr George Mitchell's political review.
Speaking after a 2 1/2-hour meeting of the Ulster Unionist Party's 100-member executive in Belfast on Saturday, Mr Trimble said: "It is perfectly obvious that if Patten gets it seriously wrong that will have serious implications for the whole process."
The UUP leader said he was aware of proposals in the report by the Independent Commission on Policing that "if implemented in Northern Ireland would lead to a corruption of policing and a corruption of the legal system".
Writing in yesterday's Observer, the Northern Secretary, Dr Mo Mowlam, promised paramilitaries would have no role in the police, that there would be consultation with political parties and any changes would be sensitively handled.
The RUC Chief Constable, Sir Ronnie Flanagan, said he would be "astounded" if Mr Patten recommended the disbandment of his force, although he admitted that significant change was "inevitable".
Sir Ronnie, who has not seen the report, warned against a hasty implementation of the changes as this would reduce the RUC's ability to protect the public from terrorism.
"These changes will require consultation and they will require legislation, and because they can only be implemented in an appropriate security situation, then clearly nothing can happen overnight," he added.
Meanwhile, the "Friends of the RUC" have launched an advertising campaign aimed at lobbying support for the force in its present form.
A spokesman for the group, which says it is independent of any political grouping, said many people were "concerned and alarmed" at recent leaks regarding the contents of the Patten report.
A former reserve policeman, Mr Ronnie Pollock, who lost both legs in an under-car bomb attack by republican paramilitaries in 1981, described the Patten commission as "a waste of taxpayers' money". Huge sacrifices made by security forces down the years were being forgotten, he added.
But a Belfast father, who was left to bring up three young children when his wife was killed by an RUC plastic bullet in 1981, said officers like the one responsible for his wife's death "must be taken out of the force and never, ever again be placed in a position of trust where they hold the lives of innocent people in their hands".