DUP MPs did not vote on a damning report that found Boris Johnson lied to Parliament over Covid lockdown parties at Downing Street.
No vote was recorded for all eight of the party's MPs when the Commons on Monday night overwhelmingly backed the Privileges Committee's findings by 354 votes to seven.
SDLP leader Colum Eastwood and Alliance deputy leader Stephen Farry voted in support of the report, which found Mr Johnson deliberately misled MPs with his partygate denials.
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No vote was recorded for SDLP South Belfast MP Claire Hanna. She said beforehand she would not be speaking in the debate but hoped the vote "starts the end of (Mr Johnson's) toxic influence".
Sinn Féin's seven MPs do not take their seats in Parliament due to the party's abstentionist policy.
Ahead of the proceedings, DUP leader Sir Jeffrey Donaldson told the Belfast Telegraph his MPs would discuss the report and determine how they would vote.
With 354 votes in favour, MPs endorsed sanctions against Mr Johnson recommended by the committee, including banning him from having a pass to access Parliament, which is usually available to former MPs.
The Tory-majority panel also concluded that Mr Johnson should have faced a 90-day suspension for misleading the House when he told the Commons that Covid rules were obeyed in No 10 despite parties taking place.
Mr Johnson was censured in his absence, having quit as an MP and labelled the inquiry a "kangaroo court" after being told in advance of its findings.
Alliance's Mr Farry, MP for North Down, said Mr Johnson had been "finally held accountable" and he should never have been "near to power".
"Huge problems in UK governance and standards in public life sadly persist," he added in his post on Twitter.
The SDLP's Mr Eastwood said the report on Mr Johnson demonstrated "just how unfit he is to hold public office".
The Foyle MP said: "The brass-necked contempt with which he has treated the public, particularly people who made enormous, life-changing sacrifices during the Covid pandemic, is shocking and it has all been in his narrow self-interest.
"It is important to rebuild confidence in the institutions of government that those who abuse the public's trust and fall so far short of the standards expected of those in public life are seen to be held to account."
Excluding Commons Speakers, no vote was recorded for 281 MPs because they either abstained or did not turn up to vote.
They included current Prime Minister Rishi Sunak and the majority of Tory MPs.
The Prime Minister's official spokesman said he had afternoon meetings on Monday, including hosting his Swedish counterpart, Ulf Kristersson, before attending a dinner in the evening.
But critics rounded on his absence, with Liberal Democrat deputy leader Daisy Cooper saying: "Tonight Rishi Sunak committed a cowardly cop-out. His failure to vote says all you need to know about this Prime Minister’s lack of leadership.
"Sunak promised integrity yet when push came to shove, he was too weak to even turn up."
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