Controls introduced in Northern Ireland due to Brexit were suspended Monday evening in the ports of Belfast and Larne due to threats to personnel.

Mid and East Antrim council on Monday night announced it was withdrawing 12 of its staff at Larne port with immediate effect due to concerns for their safety.

“In consultation with my staff I have decided to withdraw staff from Belfast and Larne ports tonight,” Edwin Poots, Northern Ireland’s minister of agriculture, wrote on Twitter.

A spokesperson for the minister clarified that while physical checks on goods had been suspended, document checks were continuing.

Tensions have emerged in loyalist communities in Northern Ireland following the introduction of checks on goods arriving from Great Britain. A protocol was introduced to control imports from Great Britain and avoid a hard border between Northern Ireland, which is part of the U.K. and Ireland, which remains a European Union member.