Four men have been arrested by detectives investigating a series of UVF murders in north Belfast as part of Operation Ballast, police said.
Three men, aged 28, 32 and 62, were arrested in the greater Belfast area and have been taken to the Serious Crime Suite at Antrim police station for questioning.
A fourth man was later arrested in the Antrim area.
These are the first arrests by Detectives from the Serious Crime Branch since the PSNI took over the running of Operation Ballast from the Historical Enquiries Team last December.
Operation Ballast investigates the crimes of an Ulster Volunteer Force gang based in the Mount Vernon estate in north Belfast.
It was set up after a damning report by former Northern Ireland Police Ombudsman Nuala O'Loan, who claimed the paramilitary killers were protected from prosecution because they were police agents.
Ms O'Loan examined the allegations on the back of a complaint by Belfast man Raymond McCord, whose son, Raymond McCord Junior, was murdered by the UVF in 1997.
The HET investigations have led to 20 people being either charged or reported to the Public Prosecution Service for a total of 23 offences including murder and attempted murder.
The HET is now concentrating its efforts on helping to answer questions for families who lost loved ones during the Troubles.
Following the arrests, police said Operation Ballast was "a large and complex investigation which will continue for a considerable time."
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