The leader of the opposition made the comment in a speech to the British Irish Parliamentary Assembly yesterday, when he warned Prime Minister Boris Johnson that he must make the protocol arrangements work.
Sir Keir said: “The importance of trust in Northern Ireland cannot be overstated. I was struck when I visited Northern Ireland last July at how low the levels of trust are at the moment, the biggest reflection I had as I left Northern Ireland. It is a dangerous and deeply concerning development.
“That trust matters. The instability over the protocol has gone on far too long. Much of it stems from the government’s deception around what it is. ‘No change for business’ was never going to match the reality – and businesses knew that themselves.”
He continued: “When it comes to the protocol, this prime minister negotiated it, ratified it, and legislated for it – and now he must make it work.
“It would be a complete dereliction of duty to block a pragmatic way forward. That will bring stability, jobs and livelihoods in Northern Ireland.”
Sir Keir also expressed concern about the collapse of the Executive, as he urged the Mr Johnson to use his position to try and broker a solution.
“I implore all parties to return to Stormont and this is a time for leadership.
He added: “The PM of the UK has a responsibility to use his position to try and broker progress. We all in this room care about the importance and future of this relationship – and will be involved in shaping it.
“So let’s resolve to meet the difficulties we face, and let’s resolve to do it together. The people of both islands expect us to – and they deserve no less.
“Together, out of the painful last few years, let’s build a stronger future and be the example the world needs of what it means to defend, value and cherish a legacy of peace.”
Mr Starmer’s speech also focused on the importance of the Good Friday Agreement.
He said: “As we face through challenging times, we must always be guided by the principles and the spirit of the Good Friday Agreement to help us navigate our way.”