Ireland’s prime minister on Tuesday condemned the intimidation of officials carrying out post-Brexit checks at Northern Irish ports as a “very sinister and ugly development”.

The intimidation led the EU Commission to temporarily withdraw its staff deployed in Northern Ireland to oversee the checks. Local officials were pulled out earlier.

Many pro-British unionists fiercely oppose the new trade barriers introduced between Northern Ireland and the rest of the United Kingdom as part of the Northern Ireland protocol, a standalone deal for the region after Britain left the EU.

Northern Ireland’s devolved government temporarily suspended some inspections at the ports of Larne and Belfast late on Monday after a local council withdrew staff over safety concerns and police said they would increase patrols.

“I would condemn the intimidatory tactics against workers … It’s a very sinister and ugly development and obviously we will be doing everything we possibly can to assist and defuse the situation,” Prime Minister Micheál Martin told reporters.

The council whose staff inspected goods at Larne Port said serious concerns around their safety were raised after a rise in “sinister and menacing behaviour” in recent weeks, including the appearance of graffiti describing port staff as “targets”.

The local mayor said he had received intelligence that people were taking down the car registration numbers of port staff.

“Its very worrying when you hear of threats against any of the people here,” a member of Larne Port staff, who would not give her name because she was not authorised to speak to media, told Reuters.

The protocol was designed to maintain the principles of the 1998 Good Friday Agreement and Northern Ireland’s open border with Ireland by keeping the region in the UK’s customs territory but also aligned with the EU’s single market for goods.

In practice, it has led to delays and in some cases the ceasing of trade in some everyday goods originating in Britain.

LOYALIST ANGER

A senior member of the Democratic Unionist Party (DUP), the region’s largest unionist party which has been calling on London to seek to remove the new trade barriers, appealed for calm, and partly blamed the European Union for acting “crassly” to try to prevent vaccine exports through the Irish border.

A “blunder” by EU officials in briefly invoking and abruptly reversing emergency powers in the Northern Ireland protocol during a showdown with Britain over COVID-19 vaccines in recent days has further angered unionists.

Responding to the criticism, an EU Commission spokesman said the intimidation originated before the furore over the emergency powers and that “whatever the reason, a threat of violence is simply unacceptable”.

The British-run region remains deeply divided along sectarian lines even after the 1998 peace deal, with Catholic nationalists aspiring to unification with Ireland and Protestant unionists wanting to remain part of the UK.

Three members of the non-sectarian Alliance party posted photographs on Twitter of similar graffiti. One read “RIP GFA,” a reference to the Good Friday Agreement.

“You shouldn’t threaten people but something has to be done,” said William Beggs, a Larne resident out walking his dog around the overwhelmingly Protestant town where some celebrate their identity and loyalty to the British crown by painting road edgings in the red, white and blue of the British flag.

“This is a loyalist town and there is a lot of anger about the border down the Irish Sea. It shouldn’t be there.”