Conservative MP Peter Bone is under investigation for expenses claims relating to the upkeep of his second home, the parliamentary commissioner for standards has said.

The claims are understood to have been made between 2005 and 2009.

MP for Wellingborough told the Times he had "done nothing wrong", adding that it was "not unusual for MPs to have their expenses challenged".

A spokeswoman for the commissioner declined to comment further.

The system for investigating alleged abuses of MPs' expenses was reformed in 2009, after a string of scandals, but cases involving claims made before 2010 still invoke the previous investigatory system.

This means that the independent commissioner investigates the allegations before submitting a report to the standards committee.

The committee, which comprises 10 MPs and three members of the public, then has the final say on whether to accept the commissioner's conclusions.