Boris Johnson must “step up” and convene all-party talks to tackle violence in Northern Ireland, Sir Keir Starmer has said as he raised concerns the Prime Minister’s Brexit promises are not being kept.

The Labour leader, a former human rights adviser to the Northern Ireland Policing Board, said on Thursday that there is “no justification” for several nights of disorder that have seen dozens of police officers injured.

But he acknowledged there are concerns over the arrangements for the nation after the UK left the European Union and he told Mr Johnson to find “pragmatic political solutions” over the rioting.

The Prime Minister has said he is “deeply concerned” by the scenes and called for calm in the region, adding: “The way to resolve differences is through dialogue, not violence or criminality.”

The violence unfolded amid increasing political tensions over the trade border in the Irish Sea caused by Mr Johnson’s Brexit agreements with Brussels, as well as fallout from the police’s handling of a mass republican funeral that took place during coronavirus restrictions.

Sir Keir said: “This is about leadership and the Prime Minister can’t be absent.

“He needs to convene talks urgently to find pragmatic political solutions to reduce this violence.”

Asked during a campaign visit to Bristol if he thinks the violence is a consequence of Brexit, the Labour leader said: “There are concerns in Northern Ireland about Brexit, there are concerns about the promises that the Prime Minister made which haven’t been kept.

“They don’t justify the violence, let’s be very, very clear about that.

“What the Prime Minister needs to do now is step up, show leadership, convene all-party talks and talk to the government of Ireland of course as well, and resolve this with pragmatic political solutions.”

The Stormont Assembly was being recalled from Easter recess for an emergency sitting later on Thursday morning to debate the violence, which has mostly flared in loyalist areas.

UK Cabinet minister Matt Hancock earlier described the reasons for the violence in Northern Ireland as “complex” as he called for dialogue.

The Health Secretary told Sky News: “Of course we’re concerned and the route out of this is dialogue and I’d encourage all sides to engage in that dialogue.

“The reasons for this violence are complex.

“I’ve spoken to the Northern Ireland Secretary and he and the Prime Minister are obviously working very closely on this.

“From the UK Government point of view we’d like to see all sides engaged in that dialogue and (for it to) be resolved as a devolved matter by the people of Northern Ireland.”