Police in Northern Ireland are investigating the possibility that a senior dissident republican shot dead yesterday may have been killed in revenge for the murder of Dublin criminal Robbie Lawlor earlier this year.

Warren Crossan was shot a number of times close to his mother's home in the Falls Road area of west Belfast.

He was chased along a street by two masked gunmen, who fired as they ran.

Police have described it as a "callous and reckless killing".

"To bring firearms onto a residential street in broad daylight simply beggars belief," said PSNI Detective Chief Inspector Darren McCartney at a media briefing this afternoon.

"The gunmen did not give any thought to the risk posed to local people in this community when they ran through the streets firing shots, at least one of which hit a vehicle owned by a resident."

Warren Crossan was arrested and questioned about the killing of Robbie Lawlor in the Ardoyne area of north Belfast in April, but released unconditionally.

At a media briefing this afternoon, DCI McCartney said links to organised crime could not be ruled out.

He was asked if police believe Warren Crossan may have been killed in retaliation for Robbie Lawlor's killing.

"It is a very early stage in the investigation and I'm ruling out absolutely nothing at this time," he said.

Asked if the PSNI is liaising with gardaí, he replied: "We have investigations ongoing throughout the length and breadth of the country."

The police will not comment on whether the 28-year-old had been warned that his life was under threat.

DCI McCartney said the PSNI is doing everything it can to ensure the killing does not result in an escalation of violence.

Warren Crossan was regarded by police as a senior dissident republican and drug dealer.

During a court hearing last year, he was described by police as a "kingpin" in a plot to smuggle cocaine into Northern Ireland.

His father, Tommy Crossan, who was also a senior dissident republican, was shot dead in west Belfast in April 2014.

Police said they believed the killing was part of an internal feud.