Some officials withdrawn from Brexit inspections at Larne Port amid safety concerns are returning to work.

Mid and East Antrim Council has said its staff would return to work at Irish Sea trade check facilities on Friday evening following the completion of a threat assessment by the Police Service of Northern Ireland and its own subsequent risk assessment.

“The health and safety of our staff remains our top priority,” said a council spokesman.

Inspectors employed by Stormont’s Department of Agriculture, Environment and Rural Affairs were also withdrawn from duties on Monday evening. That move impacted both Larne and Belfast.

The department had not yet made a decision on their return on Friday evening.

A spokeswoman said: “The department has received the findings of the formal threat assessment from the PSNI and is currently considering it alongside its own internal risk assessment.

“Any decision to recommence full checks will be informed by both documents.”

EU officials overseeing the implementation of the new checks were also withdrawn from duties on Monday.

Inspections on animal-based produce arriving from Great Britain, which are required under the contentious Northern Ireland protocol, were suspended at Belfast and Larne ports after menacing graffiti appeared.

Police blamed the graffiti and menacing online comments on disgruntled individuals and small groups and have made clear there is no evidence of wider paramilitary involvement in threats.

The council workers’ return to duties was announced as the European Commission said it was exploring all “flexibilities” available within Northern Ireland’s post-Brexit trade deal.

President Ursula von der Leyen recognised particular concern around the health certification of imported food products.

The DUP has vowed to scrap the Northern Ireland Protocol, which keeps the Irish land border open since the country follows EU regulations, following disruption to some supplies from the rest of the UK earlier this year.

Unionists and loyalists believe Northern Ireland’s position within the UK has been undermined by the new trading arrangements.

Ms von der Leyen told Northern Ireland Assembly Speaker Alex Maskey: “I can assure you that the Commission has been exploring all flexibilities available under the applicable rules of Union law and within the framework of the protocol, in order to facilitate the implementation of the protocol, whilst fully protecting the integrity of the Union’s single market and customs union.”

Stormont’s First Minister and DUP leader Arlene Foster has said unionist frustrations at the trade border on the Irish Sea must be channelled through constitutional means.

Police Service of Northern Ireland (PSNI) chief constable Simon Byrne has warned of a “febrile” atmosphere.

Mrs Foster’s sentiment was echoed by Irish premier Micheal Martin who has said parties needed to “dial down the rhetoric” over the protocol amid rising tensions.

Supermarket shelves were partially emptied of fresh goods at the start of the year and some businesses based in Great Britain were ill-prepared for the extra paperwork required when shipping goods to Northern Ireland.

Some parcel deliveries have also been affected and a series of grace periods limiting the extent of new regulatory and customs processes on incoming good from GB are due to expire as the year progresses.

On Friday, Mrs Foster welcomed the fact more than 100,000 people had signed her petition to Parliament calling for unfettered trade from the rest of the UK.

She added: “We have made the case to the Prime Minister and now the people have made a very public appeal to the Government of their country to act.

“This is not the time for more words and drawn-out processes.

“This is time for affirmative action to ensure that there is an unfettered flow of goods within the UK single market.”

Sinn Fein’s Caoimhe Archibald welcomed the Commission President’s commitment.

She said: “This shows that the EU is willing to work on practical solutions to the remaining problems which have resulted from Brexit and our exit from the EU.

“While we condemn the events of last week relating to Article 16, we are assured that the EU have learned lessons and are committed to making the protocol work.

“We call on the British government to show the same resolve by committing to proper solutions to the practical issues.”