But raising the prospect that UK intransigence could lead to a hard border with the Republic, he said it was “very clear” that the province cannot continue to enjoy access to the single market without the supervision of the ECJ.
In a speech in Lisbon on Tuesday, Lord Frost called for the wholesale replacement of the protocol, warning that enforcement powers for the Luxembourg judges meant EU law being imposed on Northern Irish citizens without democratic consent.
“That, I think, has to change if we’re to find governance arrangements that people can live with,” he said.
EU sources stressed that Mr Sefcovic’s “package of enhanced opportunities” came not in response to the Lisbon speech, but was aimed at “solving practical problems” affecting people and businesses on both sides of the Irish border, while preserving the peace and stability provided by the Good Friday Agreement.
But he took a swipe at the UK’s failure so far to deliver on data-sharing and checks on imports promised in the 2019 agreement, saying: “We are showing flexibility, but the remaining controls must be done properly.”
A UK government spokesperson said London would look at the package “seriously and constructively” and was ready to “work hard” on talks.
The CBI urged both sides to “grasp this opportunity to get back round the table and agree sustainable long-term solutions”.
And the British Chambers of Commerce warned the government not to allow its concerns over the ECJ to get in the way of a deal.
“Both sides need to reach a balanced agreement soon, focusing on cutting checks for businesses under the protocol and not disputes about different legal systems which have not been raised by the business community,” said BCC trade policy chief William Bain.
DUP leader Sir Jeffrey Donaldson said the EU’s proposals amounted to a “welcome acknowledgement that the NI protocol has not worked and does not have the consent of the unionist community in Northern Ireland”.
But he warned that the package falls “a long way short of being the basis of a sustainable solution”, as it envisaged the survival of “a protocol that has failed”.
Ireland’s foreign minister Simon Coveney welcomed Lord Frost’s promise to “engage fully” with the proposals, saying they offered a “pathway” out of the crisis.
Labour’s shadow Northern Ireland secretary Louise Haigh also said: “It is clear that with political will there is a landing ground – now is the time for the EU, UK and representatives from Northern Ireland to get around the table and reach the agreement communities need.
But the former top civil servant at the Department for Exiting the EU, Philip Rycroft, said he was “puzzled” by London’s fixation on the ECJ issue, which the UK had known was an EU red line from the start.
“Seeking to overturn that does beg a question about what the UK thought it was signing up to?” he told Times Radio. “And indeed its resolve to stick with the protocol for the long term.”