The PSNI Chief Constable Hugh Orde has apologised for the way officers raided Sinn Fein offices at Parliament Buildings, Belfast on Friday.
Mr Orde insisted the investigation into the alleged Republican infiltration at Stormont was fully justified but he admitted it could have been done more sensitively.
Up to 19 uniformed officers and two plain-clothes detectives piled into the offices as part of a series of searches.
But as he arrived for talks with Northern Ireland Secretary Dr John Reid on the emergency which has threatened to bring down Northern Ireland's power-sharing government, the Chief Constable said he was not happy.
He said: "I regret the way it was done. You can take that as a general apology."
Mr Orde accepted there had been an "error of judgment" in how police handled the planned raids.
Sinn Féin's policing spokesman Mr Gerry Kelly described the Chief Constable's comments as "weasel words".
Mr Kelly claimed the search of his party's office was "bogus".
"Its aim was to veil a direct political intervention by the PSNI. It proved to be a thin and wholly transparent veil. It was political theatre that has rebounded.
"Hugh Orde's weasel words about the manner in which this was done cuts no ice. The PSNI, like the RUC, is operating to a unionist agenda."
He was speaking after a further raid took place on a house in the Andersonstown area in west Belfast. PA