A European Commissioner has given a guarantee to an Oireachtas committee that Article 16 of the Northern Ireland Protocol will not be triggered again as happened in January.

Mairead McGuinness, Commissioner for Financial Services, Financial Stability and Capital Market Union, appeared before the Joint Committee on European Union Affairs.

She was responding to Dara Calleary, Fianna Fáil, who asked for reassurances that the "couple of hours of madness" in which the Government was "blindsided" would not happen again.

"It certainly won't happen again", the commissioner insisted, and added: "I can give you absolute guarantees around the system in place" which has "onerous requirements".

"I am a little worried when our UK friends bring this up all the time... I think it's inappropriate at this stage", Ms McGuinness said.

She noted that the EU had apologised for the mistake and called on the UK to apologise for its unilateral action.

The commissioner said that the UK's reaction to the EU's offer to extend the Northern Ireland Protocol was "quite shocking" and "lacks any graciousness".

"We are not planning to offer an extension to the extension", she told the committee.

"There was no acknowledgement of the work we have done here at EU level", Ms McGuinness said, and expressed concern that come September, the UK will continue "to point the finger" and "to refuse to acknowledge what it signed up to in the Protocol".

She warned that this would mean that "the problem gets worse", but rejected the notion of hitting back, saying that it is "not wise to talk about retaliation - it's not our style".

"I think in the long run, politeness and good manners matter. Diplomacy matters.", she said, but added that "plans are being made" and "will be revealed...if we don't see cooperative implementation of the protocol".

In a wide-ranging questions and answers session, the commissioner was asked about the OECD's moves to agree a global corporate tax rate.

"I don't see undue pressure being put on Ireland", she replied, adding that the European Commission understands Ireland's perspective, but hopes it will "join with the rest of the EU".

She said that adoption of the measures would be "a success for multilateralism".

The US is now "back at the table", Ms McGuinness affirmed, noting that the Biden administration is strongly supportive of the measures.

"The EU is very keen there is a global agreement", she told Fianna Fáil's Sean Haughey.

In relation to Belarus the commissioner told the committee that her office is directly involved in drafting and monitoring sanctions and said that sanctions are "having an impact".

She warned that "we have to try and avoid... impacting those who are not part of the problem" but said further sanctions will be imposed if necessary.

Ms McGuinness said that in the Commission there is "total commitment to insist that rule of law and values are respected", and criticised Hungary's discrimination of LGBTQ+ people as being "completely against the rights of individuals and the things that we hold dear".

"This is not acceptable", she said. "You cannot pick and choose and you cannot discriminate", she added, and promised: "Whatever we need to do will be done."

The commissioner congratulated the Irish Government on the roll-out of the vaccine programme, saying it is "regarded as one of the greatest successes".

"Europe should be proud of what we have achieved" in this regard, despite a "difficult start", she said, noting that the bloc has exported vaccines.

"How cheeky we were to think Covid would be a three day wonder", she told the committee.