Alan McQuillan said he coould not give guarantees

But it later admitted the murder, and on Tuesday issued a statement ordering the Red Hand Defenders - the name being used by an element in its own ranks - to stand down.

In response on Wednesday a statement was issued in the name of the Red Hand Defenders saying its members would stand down by midnight.

Speaking after meeting the union representatives, Mr McQuillan said that following analysis of the series of statements from the Red Hand Defenders and the UDA/Ulster Freedom Fighters, it was now clear the initial threat against Catholic postal employees "did not come from those who murdered Mr McColgan".

Mr McQuillan added he had made it clear to the union that he was "90% sure" the initial coded call making the threat "was not a genuine call".

UDA has used Red Hand Defenders cover name

He added: "However, there is always that 10%, that is why we have had such an extensive operation across north Belfast in the last few days to try to deal with anything and to try to reassure the public.

"I said quite openly to them that this is Northern Ireland and nobody can give you any guarantees."

Mr McQuillan said the Red Hand Defenders had been defunct as an organisation for some time and its code words were well known in loyalist circles.

"Virtually anybody with 20p can now phone up and claim to represent that organisation, that is the difficulty we face," he said.

Post stoppage to end

Following the assessment, the Communication Workers Union recommended to its members that the stoppage which followed the threats should end.

Northern Ireland director of Consignia, which runs Royal Mail, Sir John Semple, also said he now believed he was "in a position to call upon all our staff to come back to work".

There have been no deliveries in many areas of the province since Saturday.

Many postal workers stayed away from work on Tuesday to attend Mr McColgan's funeral and Royal Mail said on Wednesday there was a "patchy service" around the province.

Alban Maginness: "UDA must restore its ceasefire completely"

Postal workers, fire service workers and employees in many other sectors have been asked by the Irish Congress of Trade Unions to take part in a stoppage on Friday afternoon.

Rallies around the province are to be held in protest at paramilitary violence against workers.

Meanwhile, reacting to the 'Red Hand Defender' statement, north Belfast assembly member for the nationalist SDLP Alban Maginness said he felt it was "a joke".

"I believe the UDA have been responsible for the murder of Mr McColgan. They have admitted that themselves.

"They are responsible for the other threats and they have been responsible for a whole series of attacks over many months and it is up to them to convince the public that their ceasefire is going to be restored completely."

Sinn Fein's Alex Maskey said he had little confidence in either the UDA/UFF or the Red Hand Defender statements.

He said: "I do hope that these statements represent a breakthrough, but I would reflect the community's view that we will have to be very, very sceptical about them."

However, the DUP's Ian Paisley junior said the threats were a hoax.

He said the stoppage organised for Friday afternoon by the unions would only give credence to those who made the threats.