The PSNI has announced it will launch a four-year murder probe into the deaths of 13 people shot by soldiers on Bloody Sunday in 1972.

Police and the Public Prosecution Service reviewed the findings of the Saville Inquiry, which said none of the people killed was armed.

Chief Constable Matt Baggott announced the investigation to the Northern Irleand Policing Board yesterday, saying: "It is a matter that I think we should be investigating and will be investigating."

30 detectives are expected to work on the probe, which will take at least four years.

The chairman of the Police Federation for Northern Ireland, Terry Spence, said that prosecutions would follow if there was sufficient evidence of criminality by police officers or Army personnel.

But he questioned the wisdom of the investigation being run by the PSNI when the Historical Enquiries Team exists specifically to look into murders carried out during the Troubles and estimated that the probe would cost more than £10m.

Following the announcement Northern Ireland's First Minister Peter Robinson said the police inquiry should examine the role of his Executive colleague Martin McGuinness.

The Deputy First Minister is known to have been active in the IRA at the time.

Mr McGuinness said he would have no problem co-operating with the investigation and rejected claims that he was armed with a machine-gun on the day of the violence.

Mr Robinson of the DUP and Sinn Fein's Mr McGuinness hook hands in public for the first time on Tuesday, after four years of heading the Northern Ireland Assembly together.

(NE)