The DUP has called for an investigation into the SDLP's claims that it ensured the Policing Board appointed Sir Hugh Orde as Chief Constable of the PSNI.
Sir Hugh Orde criticised nationalist politicians
Sir Hugh, in a memo sent to almost 10,000 police officers, has also reacted angrily to the suggestion and also to remarks by Sinn Fein last week.
He said both parties were "using policing as a political football".
Sir Hugh, who is in the US, also said they were making insulting comments about the PSNI and its staff.
'Solely on merit'
Sir Hugh was angered by remarks by Gerry Adams last week, when he said republicans "would put manners on the police".
He was also annoyed by a statement by Mark Durkan in a newspaper advert in which the SDLP leader claimed his party had ensured that the Policing Board appointed Sir Hugh as chief constable of the PSNI - to keep out what he called "the old RUC order."
A spokesman for the Policing Board said it undertook a "thorough, professional and legislatively compliant appointment process".
This had been based "solely on merit and included independent assessments", he said.
"The chairman of the board has written to the leader of the SDLP in relation to comments published in an advert in the Irish News on Friday 26 January 2007. "The matter will be raised at the Policing Board meeting next week," said the spokesman.
Two former RUC assistant chief constables have consulted their lawyers over the claims.
The two unsuccessful candidates who were interviewed for the job are Alan McQuillan and Chris Albiston.
Policing Board member Ian Paisley Junior has called for an investigation into the SDLP's claim.
"This is one of the most senior appointments in Northern Ireland," he said.
"They are entitled, by dint of their membership of the Policing Board, to sit on the recruitment panel and yet this advert implies that they openly rigged that recruitment process."
Ulster Unionist board member Fred Cobain called on Mark Durkan to apologise for his remarks.
The SDLP's Alex Attwood rejected the criticism and said his party had not excluded any RUC officer from the process, but had resisted government pressure to exclude external candidates.
The SDLP leader refused to apologise to Sir Hugh and the other applicants. Mr Durkan denied the advertisement was insulting and provocative.
Meanwhile, Sinn Fein leader Gerry Adams said it was "quite ridiculous" that Sir Hugh's memo was referred to as "confidential".
"This is the PSNI showing its sensitive side. The fact is, the O'Loan report said that a serial killer was being paid taxpayers' money."
Prime Minister Tony Blair has told the Commons that Special Branch officers criticised in the report "were a minority within the police force".
Mr Blair said collusion was wrong and was to be deeply regretted.
"I don't think that should take away from the work that the majority of officers, both in the police and in the service, the majority of the work that they did was of enormous benefit to the local community."