The DUP is to investigate claims MP Ian Paisley failed to declare another luxury holiday to parliamentary authorities.
A spokesman described the allegations levelled in a BBC NI Spotlight investigation as "very serious", and said party officers would be considering them.
Tuesday night's programme claimed a Paisley family holiday to the Maldives in autumn 2016 was paid for by the Indian Ocean nation's government.
The trip came months after Mr Paisley travelled to the country on parliamentary business. The North Antrim representative had argued against sanctions being taken against the Maldives over alleged human rights abuses.
Mr Paisley denied the holiday was paid for by the authorities in the Maldives and said he is satisfied he did not need to declare the trip on the register of interests at Westminster.
The MP said he paid for part of the holiday himself, while the rest was paid for by a long-term friend who was unconnected to his work. He declined to reveal the identity of the friend.
The claims aired by Spotlight came days after Mr Paisley returned to Parliament having served a 30-day suspension for failing to declare two holidays paid for by the Sri Lankan government and lobbying on its behalf.
He narrowly avoided facing a by-election after Parliament's first ever recall petition fell short of the number of constituent signatures required to oust him by around 450.
He was suspended from the DUP pending a party investigation into the Sri Lankan controversy but the censure was subsequently lifted.
This morning, a DUP spokesman said: "The party officers will want to consider these very serious matters being mindful of the high standards we require of elected representatives."
In a statement in response to the programme, Mr Paisley said: "The government of the Maldives did not organise or pay for my family vacation in 2016, which I do not intend to go into with you.
"I'm satisfied the vacation did not have to be recorded on the register."
Read more:
- Ian Paisley under the Spotlight again for undeclared trip to Maldives
- Ian Paisley is suspended from Parliament for 30 days over free Sri Lanka trips
- Ian Paisley has made headlines before - for all the wrong reasons
SinnFéin deputy leader Michelle O'Neill said Ian Paisley should have resigned "months ago".
"It's the latest in a long line of scandals associated with the DUP and Ian Paisley in particular," she said.
"I think Ian Paisley should have resigned many months ago and I think where he finds himself again today at the centre of another scandal is not anything befitting of someone who holds public office."
At last month's party conference in Belfast, DUP leader Arlene Foster apologised after acknowledging that standards of conduct within the party had fallen short in a number of areas.
At a press conference today Ms O'Neill said: "I think that what we need to see now is more than fine words at a party conference, I think those fine words need to be acted upon and I think this will be the first test of Arlene Foster's comments at her party conference."
She added: "He should have resigned a long time ago."
SDLP leader Colum Eastwood also called for Mr Paisley to resign.
"It really is time for Ian Paisley to resign," he tweeted.
"If he doesn't, then the onus is on Arlene Foster (party leader) to remove him from the DUP."
Sinn Féin MLA Philip McGuigan said he had written to the Parliamentary Commissioner for Standards asking her to investigate the allegations.
The North Antrim MLA said "serious questions" had been raised by the latest allegations.
"The public is entitled to know who paid for this holiday and why Ian Paisley had not registered the trip with the authorities at Westminster," he said.
Mr Paisley's record suspension from Parliament was imposed following the findings of an investigation by the Parliamentary Commissioner for Standards.
nown whether commissioner Kathryn Stone intends to launch an investigation into the latest claims, as she is prevented from publicly confirming details of any probe until it concludes.
A spokeswoman for the commissioner said: "The House of Commons took a decision on July 19 2018 that the Commissioner should not publish information, other than statistics, about complaints received and about inquiries started, unless and until she had concluded an inquiry and her decision had been published.
"I can therefore neither confirm nor deny whether the Commissioner has received a complaint, nor whether she has begun or might begin an inquiry."
Mr Paisley has been MP for North Antrim since 2010.
His father Ian Paisley, a former first minister of Northern Ireland and Democratic Unionist leader, had previously held the seat since 1970.
