Reform UK leader Nigel Farage is under investigation by the parliamentary standards watchdog for a potential breach of MPs’ rules on financial interests.

On Wednesday, the standards commissioner announced he is looking into a possible breach by Farage of rules which require MPs to list income and financial benefits within 28 days.

The inquiry was launched after a complaint by a member of the House of Lords, according to a spokesman for the Reform UK leader.

Farage has not said which peer referred him but told the Telegraph newspaper he could “explicitly state” that the matter did not relate to “any undeclared income”.

According to the Parliament website, the parliamentary commissioner for standards Daniel Greenberg opened an investigation on Monday.

The investigation is into rule five, which requires MPs to “register all their current financial interests, and any registrable benefits” within 28 days.

A spokesperson for Farage said: “Following a complaint from a member of the House of Lords, the commissioner for standards is doing his job.”