Ian Paisley has been suspended by the Democratic Unionist Party and will also be excluded from the House of Commons for 30 sitting days from September 4 following a major breach of parliamentary rules.
Electoral authorities in Northern Ireland are to begin drawing up measures which could see the North Antrim MP face a by-election if enough constituents demand it.
He vowed to fight for his seat after failing to declare two luxury family holidays paid for by the Sri Lankan government. In March 2014, he lobbied against a proposed United Nations resolution to investigate alleged human rights abuse during a civil war in Sri Lanka without declaring his financial benefits.
If 10pc of his constituents sign a petition, an election will be called. A DUP statement said: "The party officers have decided to suspend Mr Ian Paisley MP from membership of the party pending further investigation into his conduct."
Sinn Fein deputy leader Michelle O'Neill said Mr Paisley was given the most serious sanction handed to any MP since 1949.
"When you consider some of the sleaze, corruption and criminal scandals that have engulfed the British Parliament during that time, that is quite extraordinary," she said.
Patrick Corrigan, head of Amnesty International in Northern Ireland, said the victims were those killed in Sri Lanka.
"Mr Paisley saw fit to lobby the prime minister against a UN investigation into gross human rights violations, including the mass killing of civilians at the end of the Sri Lankan war, for which no adequate investigation has ever been carried out."
Mr Paisley said he deeply regretted his actions and said: "There are also some who would have me booted out of Parliament and a by-election called to fill that vacancy.
"They are opportunists, some with questionable motives, and I can tell them that I have no intention of going quietly into the night."