LONDON — Senior politicians from Britain, Northern Ireland and the European Union were meeting Wednesday in a bid to defuse post-Brexit trade tensions that have shaken Northern Ireland’s delicate political balance.

British Cabinet minister Michael Gove, European Commission Vice President Maros Sefcovic and the leaders of Northern Ireland’s Catholic-Protestant power-sharing government will hold a video conference to discuss problems that have erupted barely a month after the UK made an economic split from the 27-nation EU.

Northern Ireland authorities halted veterinary checks and withdrew border staff this week from Belfast and Larne ports after threatening graffiti appeared referring to port workers as targets, and staff reported seeing people writing down vehicle license plate numbers.

The border checks on goods entering Northern Ireland from the rest of the UK are a contentious product of Brexit.

Since the UK left the European Union’s economic structures at the end of 2020, customs and veterinary checks have been imposed on goods moving between Britain and the bloc — and on some British goods going to Northern Ireland, because it shares a border with EU member Ireland.

The checks are strongly opposed by pro-British Unionist politicians, who say they drive a wedge between Northern Ireland and the rest of the UK. They are calling on the British government to rip up a section of its divorce agreement with the EU known as the Northern Ireland Protocol, which gives the region a separate trade status to the rest of the UK.

The Democratic Unionist Party, which heads the power-sharing Belfast administration, is refusing to cooperate with the Irish government on implementing the new rules.

Northern Ireland Deputy First Minister Michelle O’Neill, from the Irish nationalist party Sinn Fein, accused the DUP of stirring up tension with its “reckless” attacks on the Brexit agreement.

“The DUP needs to step back from throwing the baby out with the bathwater, what we need to do is be calm, be steady and work our way through these issues,” she said.

Police have warned that violent pro-British Loyalists could capitalize on the tensions, though they say the current threat appears to come from a small number of individuals rather than paramilitary groups.

The sensitivity of Northern Ireland’s status was underscored last week, when the EU threatened to ban shipments of coronavirus vaccines to Northern Ireland as part of moves to shore up the bloc’s supply. That would have drawn a hard border on the island of Ireland — exactly the scenario the Brexit deal was crafted to avoid.

British, Irish and Northern Ireland politicians all expressed alarm at the plan, and the EU dropped the idea.

The UK government is urging the bloc to take a more light-touch approach to border checks, which have already led to shortages and delays in getting some goods to Northern Ireland. In a letter to Sefcovic, Gove called for short-term grace periods that have delayed imposition of full red tape on supermarket supplies, parcels and medicines to be extended until at least 2023.

Gove said the UK would use “all instruments at its disposal” if a solution could not be found, in a suggestion Britain could trigger an emergency clause allowing it to deviate from the Northern Ireland Protocol — the same measure the EU briefly planned to invoke last week.

British Prime Minister Boris Johnson accused the EU of undermining the protocol with its vaccines move, and said the UK would “do everything we need to do … to ensure that there is no barrier down the Irish Sea.”

Sefcovic tweeted that protecting peace in Northern Ireland “has always been EU’s absolute priority.”

He said the Northern Ireland Protocol was “the only way to protect Good Friday (Belfast) Agreement in all dimensions, protecting peace & stability on the island of Ireland.”