Brussels dumped more than 800 new pieces of regulation upon Northern Ireland without notice, according to Cabinet Office officials, in a move criticised by a senior minister.

Brexit minister Lord Frost told peers that the development showed the European Union was failing to take “seriously” that it was making laws “for another territory” after Brexit.

The comments come after the Cabinet Office said Brussels sprung an update on it that more than 600 new measures impacting upon Northern Ireland had been adopted by the bloc in the past three months, with a further 200 in the pipeline.

The Northern Ireland Protocol is aimed at avoiding a hard border with Ireland by effectively keeping Northern Ireland in the EU’s single market for goods.

The move, much to the annoyance of Unionists, means the region continues to follow Brussels rules while not having a say in them.

The Joint Consultative Working Group was set-up as part of the UK’s divorce deal with the bloc in order to give businesses in Northern Ireland advanced notice of regulation changes related to the Protocol.

I think the least that can be done is to give some advance warning, and that’s not really happening at the moment

But peers on the Lords Protocol on Ireland/Northern Ireland Sub-Committee were told on Wednesday that the EU gave the working group a list of 800 new regulations without prior warning, with more than 600 already agreed by Brussels.

Rebecca Ellis, director of the Northern Ireland/Ireland Unit in the Cabinet Office, said efforts to ensure the working group gave advance notice on changes was “still not there”.

“We had what you might call a ‘drop’ of new measures last Thursday which included a list of over 800 measures, I think 666 of which had already been adopted,” said the official.

“And in many respects there was no more information provided than what you could read in the official journal.”

Lord Frost confirmed those details when raised later by Conservative peer Lord Hannon, announcing it to be a “problem” in the current set-up.

“Obviously the Joint Consultative Working Group is supposed to give us advanced warning – if all it’s doing is giving us what’s in the official journal in some other form, then there is not really a lot of point in it,” he said.

“It needs to give some upstream warning and I think the way it is working at the moment is a bit indicative of – how should I put it? Not taking entirely seriously that the EU is legislating for another territory – these are laws that are imposed on another territory without a process.

“I think the least that can be done is to give some advance warning of that, some understanding, some chance to feedback and consult, and that’s not really happening at the moment.”

The former MEP and Brexit campaigner Lord Hannon replied: “It seems to me, prima facie, to indicate a striking lack of goodwill and good faith.”

During the session, Lord Frost – who negotiated Britain’s EU exit – refused to comment on whether the Protocol was “fit for purpose”.

He argued, as he has done so previously with Northern Ireland Secretary Brandon Lewis, that both sides need to strive for a “new balance” in the post-Brexit terms.

Asked whether the Protocol was fit for purpose he said: “I’m not sure I would characterise it that way or make a judgment on that point.”

Pressed on why he would not take a stance, the Cabinet minister replied: “Because we need to find out – and that’s what we’ve been trying to do over the last few months – whether it is possible to operate these arrangements in a way that gives a different balance.

“That is the kind of discussion we have not had with the EU, but would like to.”