Police acted lawfully during the process of drafting letters to IRA suspects on the run, Northern Ireland's chief constable has said.

Northern Ireland's First Minister Peter Robinson has questioned the legality of parts of the political process, which led to people receiving secret assurances that they were not wanted for questioning.

PSNI Chief Constable Matt Baggott privately briefed the Policing Board of politicians and independent members, which oversees the police.

Board chairman Anne Connolly said: "The chief constable told the board that the PSNI actions in this process were legitimate and lawful and that the PSNI do not believe the letters confer an amnesty."

Letters were sent to about 200 people by the Northern Ireland Office (NIO) after a search of police records to identify if they were wanted in connection with crimes.

In John Downey's case, he was sent the letter in error after the computer system failed to reveal that he was sought by the Metropolitan Police for questioning over the Hyde Park bomb.

Mr Baggott has also pledged full PSNI co-operation in the Police Ombudsman for Northern Ireland investigation and the independent inquiry announced by British Prime Minister David Cameron.

Preparatory work has begun in support of both of these.

The board reviewed its files for information about on-the-runs.

Ms Connolly added: "It is not possible to determine from the documents held the level of detail provided to the board and whether information on the role and work of the OTR unit was briefed to the board.

"The first detailed record which provides substantive information on the PSNI approach to the review of information is in 2010 when questions were raised in board public session and correspondence is received from assistant chief constable crime operations."

A police spokesman said: "The chief constable Matt Baggott confirmed to the Policing Board today that the PSNI acted legitimately in carrying out their role in this process and that he would be complying fully with the judge's review and with the Police Ombudsman investigation."