DUP MP Ian Paisley Jr has been suspended from the House of Commons for 30 days after failing to declare two family holidays paid for by the Sri Lankan government.
The Commons Standards Committee recommended the "severe" punishment over allegations that Paisley failed to officially register the £100,000 (€112,000) trips in March and July 2013 with the House of Commons’ Register of Members’ Financial Interests.
The Committee called for the North Antrim MP to be "suspended from the service of the House for a period of 30 sitting days starting on 4 September 2018."
Following the holidays, Mr Paisley wrote to then home secretary Theresa May in support of the Sri Lankan government over a proposed UN resolution.
A Commons report found that these actions amounted to "paid advocacy" and added that Paisley had brought the House into disrepute.
Paisley, 51, is one of 10 DUP MPs propping up the current minority Conservative Government under Theresa May.
His suspension, which is the longest handed out in 15 years, comes as Mrs May needs all the votes she can get to support proposals on UK Brexit policy.
Commons rules state that MPs must declare any foreign visit which "relates in any way to their membership of the House or to their parliamentary or political activities" and which costs more than £300 - unless self-paid.
MPs do not have to register family holidays as long as they are "wholly unconnected" to parliamentary or political activities".
Members who are suspended from the Commons for more than 10 days are open to a recall petition.
If more than 10 percent of Mr Paisley's North Antrim constituents were to sign such a petition calling for his removal, the seat would be declared vacant and a by-election would follow.