The SDLP has delayed its response to the revised policing implementation plan, saying it would give the document urgent consideration over the weekend.
SDLP acceptance of the plan is considered crucial for it to get widespread support among nationalists. However, the party's policing spokesman, Mr Alex Attwood, said it would have to study it carefully to see whether it was "sufficiently close to the spirit of Patten".
"The SDLP has received a copy of the plan and welcomes its publication. This was a key requirement, outlined to the British government arising from the Weston Park proposals," Mr Attwood said.
"The plan is a substantial document and requires substantial consideration. Each line of this document will be fully and carefully assessed by the SDLP.
"The SDLP has fought hard in Westminster and elsewhere over the last two years to retrieve Patten from the Mandelson legislation. Policing is so central and crucial to the future of the people of the North of Ireland that it requires serious judgment, not snap judgment."
Mr Attwood criticised Sinn Fein for what he described as its "summary dismissal" of the plan. "The document outlines proposals, both in law and in practice, that require serious assessment by those really committed to a new beginning for policing and not summary dismissal," he said.
Earlier, Sinn Fein described the document as "seriously flawed", saying it failed to provide a clear route towards the new beginning to policing promised in the Belfast Agreement.
Addressing a press conference, the party chairman, Mr Mitchel McLaughlin, said the published plan represented "a failure of leadership by the British government.
"It is a seriously flawed plan which fails to meet the threshold for a new beginning to policing set out by the Patten Commission. On that basis, our party is not in a position to accept the plan as it currently stands."
Mr McLaughlin said that following an "exhaustive, line-by-line analysis" of the plan, his party had reached the conclusion that it did not go far enough.
"In other words, the fault lines in the plan will prevent the nationalist and republican community from joining or supporting this police service."
The main "fault line", according to Sinn Fein, is the fact that many of the proposals are dependent on the assessment of the security situation by the Chief Constable and, in a wider sense, the Northern Secretary.
The party is also unhappy about the restricted powers of the Policing Board and the Ombudsman.
"In light of all of this, it is Sinn Fein's considered view that the implementation plan on policing does not bridge the gap between the Mandelson legislation and the Patten report," the party said.
"In that context and at this time Sinn Fein will not be making appointments to the policing board," the party chairman concluded.