Northern Ireland’s department of agriculture has said it is acting to mitigate where it can as workers in ports and meat factories take part in a five-day strike.

The action over pay started at midnight on Sunday and is to continue to Friday.

The ports of Belfast, Larne and Warrenpoint as well as meat processing plants are being affected by the action, which started at midnight on Sunday.

Members of the Nipsa union, who work across the Veterinary Service Animal Health Group in the Department of Agriculture, Environment and Rural Affairs (Daera), are taking part in the strike, which is planned to run until Friday.

They are involved in checks on animals and some food products entering Northern Ireland from Great Britain.

Both green and red lanes at ports are expected to be affected, and it is anticipated that the strike may lead to ports either shutting down imports of some products or not carrying out checks required by the EU.

The Ulster Farmers’ Union (UFU) said the strike has come at the “worst possible time”, in the lead-up to Christmas.

UFU deputy president John McClenahan said members understand the reason for the strike action, but feel it is “a bit unfair” for farmers, who, he said, will “pick up a substantial cost”.

“It’s going to have a massive impact, and I suppose that’s one of the difficulties – we don’t at this stage fully understand what that impact is going to be,” he told the BBC.

“That level of uncertainty is probably the worst aspect of it – you can’t plan for what you don’t know.

“It’s the worst possible time, a lot of our factories are looking at that run-in to Christmas and they are increasing their capacity to satisfy that Christmas demand, and that starts now.

“It’s probably not coincidental that the strike has been called to coincide with that, but that only increases the pressures that it puts on our farmers.”

Nipsa said the action is in protest at a pay award of £552, between 0.5% and 2%, given to all civil servants in Northern Ireland for 2022/23, at a time when inflation was above 10%.

General secretary Carmel Gates said public sector workers have seen their living standards crash.

She told the BBC that Northern Ireland Secretary Chris Heaton-Harris has refused to engage with the union.

“The Northern Ireland economic sanctions have caused real suffering for ordinary working-class people,” she said.

“Public sector workers have seen their living standards crash.

“There is now a hard ‘pay border’ between workers in Northern Ireland and workers across the Irish Sea.

“I commend and thank these workers who are taking this action on behalf of their Civil Service colleagues but also on behalf of all public servants here.

“It is time for the Secretary of State to listen to the ordinary people, meet with unions and direct senior civil servants to engage in meaningful negotiations to end this dispute.”

A Northern Ireland Office spokesperson said the Secretary of State “would be happy to meet with representatives from Nipsa”, but said the UK Government “has no authority to negotiate public sector pay in Northern Ireland”.

“The Secretary of State’s priority is to see the return of locally elected, accountable and effective devolved government, which is the best way for Northern Ireland to be governed,” they said.

A Daera spokesman said the department “respects the rights of its staff to take industrial action and deeply regrets that the 2022 Nics Pay Award could not have been higher due to the very challenging budgetary position”.

They said the department is taking action to mitigate where it can.

“As soon as the likelihood of this strike action became apparent, the department commenced its business continuity planning and in the period since then has engaged extensively with stakeholders and operators on the potential impacts,” they said.

“It also advised operators of businesses that rely on Daera services to consider activating their own business continuity/emergency plans.

“Nipsa has granted derogations to ensure that poultry slaughter continues and for the provision of cover for the 24-hour epizootic on call rota.

Both have been granted on the basis that they will only take effect if required. Other requests for derogations were not granted.

“As of today (Monday), Daera has been able to provide some level of service to the intensive livestock sector and is monitoring activities across portal and field operations and, where possible, is taking action to mitigate the worst impacts on service delivery.

“We are keeping the situation under review and engaging with our stakeholders to inform them of what level of service they can expect.

“It is important to note that while some limited mitigations are available to us, any steps taken must be in line with the relevant legislation and Nics policy governing strike action.

“Advice on all sectors affected can be found here: Sectors Affected by Planned 5-day Industrial Action October 30 – November 03 2023.pdf (daera-ni.gov.uk).”