It was business as usual in Belfast on Saturday

Royal Mail said there was a backlog of seven million items, but that mail was now moving to Britain and deliveries in Belfast had commenced again.

Extra people and vehicles are being brought in and the company is using other mail centres across the UK to help process undelivered post.

However, it is expected to take up to four weeks to clear the backlog.

Royal Mail had asked staff to go back to work after it agreed to a review of employee relations.

The strike ended on Friday after agreement between the company and the Communication Workers Union.

The union said its members regretted the inconvenience the strike had caused to the public.

In a statement on Saturday, Royal Mail said all staff returning to work had attended "welcome back" meetings.

"These have been useful and constructive sessions for employees and managers," it said.

The backlog is expected to take several weeks to clear

"They have been a forum for employees to start feeding back issues and for Royal Mail to get commitment to a shared understanding of the way forward, including the work of an independent third party and the need to agree a flashpoint resolution process that will ensure that there will be no form of industrial action over the next 12 months."

On Friday, Royal Mail's personnel head in Northern Ireland, Gary Crawford, said the strike had been "completely unnecessary".

A CWU spokesman said it was clear there had been a "long history of poor industrial and employee relations within Royal Mail" in Belfast, which led to the dispute taking place.

"At the request of Royal Mail, the union became involved in discussions to help resolve the dispute and is pleased that Royal Mail has now given a written statement to the union, via the Labour Relations Agency, which has enabled the dispute to be brought to an end and facilitated a return to work."

Workers at Tomb Street in Belfast began an unofficial strike on 31 January after staff alleged harassment by managers. Royal Mail denied the claims.

It halted all deliveries of post in north, south and west Belfast, as well as all mail being sent to Britain.

Industrial action

The union had said it wanted assurances from the company that it would not interfere with the independent body brought in to review employee relations at the firm.

It also said it did not want its members victimised when they returned to work.

On Thursday, the company said it had given the union the assurances it had asked for.

The company's offer also required staff to agree to a 12-month ban on industrial action.

The Federation of Small Businesses welcomed the end of the strike and urged Royal Mail to move quickly to clear-up the backlog of mail.