Lord David Frost, Boris Johnson’s EU minister, has warned Brussels it needs to “rapidly” rethink its approach to post-Brexit Northern Ireland trade rules as the new political leader of the region’s largest party vowed that he “will not rest” until they are torn up.

Frost is expected to meet Maros Sefcovic, European Commission vice-president, next month to try to defuse the political crisis over “the border in the Irish Sea” and avoid the annual summer season of pro-UK unionist parades in Northern Ireland descending into the kind of violence that marred the streets in April.

Friday evening’s election of Edwin Poots, a hardline unionist, as leader of the Democratic Unionist party has added to pressure on London and Brussels to calm tensions in the region.

Downing Street is nervously eyeing the date of July 12 — the anniversary of the victory of the protestant William of Orange over the deposed Catholic king James II in 1690 — as a particular flashpoint. Poots has spoken of his desire to secure a “win” on the Northern Ireland protocol by that date, a person familiar with the situation told the FT.

Frost, writing in the Mail on Sunday, claimed that the EU was fuelling tensions by an over-rigorous interpretation of the checks needed on trade between Great Britain and Northern Ireland under the NI protocol. “If the protocol operates so as to damage the political, social or economic fabric of life in Northern Ireland, then that situation cannot be sustained for long,” he said.

Frost said that if the EU did not soften checks at ports on the Irish Sea then the UK government would consider “all our options”. Johnson has indicated that includes possibly suspending the checks under Article 16 of the protocol.

Poots told Belfast’s Sunday Life that the protocol was “by far the biggest issue” on his plate and that ultimately it would need to be “fundamentally changed [or] removed to take things forward.”

He said unless there was “significant political progress made in the coming weeks” he would consider going to court to ask for a judicial review of the protocol. Unionist leaders are already pursuing a challenge against the deal in Belfast’s courts.

One DUP source, who did not back Poots’ leadership bid, told the FT that the new leader’s options for opposing the protocol were limited, since the deal is between the UK and EU.

Possible options open to Poots would be for Northern Ireland’s agriculture department, which he leads, to slow down recruitment of officials to carry out checks at the border.

Poots also told Sunday Life that he would boycott meetings of the North/South Ministerial Council, where leaders from the Republic of Ireland and Northern Ireland discuss policy issues.

The nuclear option is shutting down Stormont’s parliament over the issue, which would ultimately trigger elections. Party insiders do not expect the incoming DUP leader to resort to this since the DUP is lagging in the polls. Northern Ireland’s public is still smarting from three years without local government after power-sharing collapsed in 2017.

Frost’s comments will rankle EU officials, who point out that Brexit has caused the problems and that Johnson himself supported the protocol as a means of managing the border issue.

João Vale de Almeida, EU ambassador to London, recently said Brussels was looking to help ease problems at the border. “We are not here to excessively complicate the lives of people and businesses in Northern Ireland,” he told the FT.

But Frost claimed Brussels did not appear to share Britain’s desire for “free trade and friendly relations”, citing recent French threats to turn off power in Jersey or to punish the City of London in a dispute over fishing rights.