The head of the United Nations’ environmental agency has been strongly criticised for his frequent flying in a report raising doubts over his environmental concerns.

Erik Solheim, a 63-year-old Norwegian former environment minister, spent 529 of his first 669 days in the job travelling, according to a draft UN report obtained by Norway’s Aftenposten newspaper.

The UN’s office of internal oversight services (OIOS) claimed that Mr Solheim spent 79 per cent of his time away from the agency’s Nairobi headquarters.

The auditors accused him of taking a flight from Washington DC to Paris for the weekend, before boarding another flight to New York.

In total he spent 90 days in Oslo and Paris, with some of the trips registered as “bilateral meetings” – despite taking place on weekends or during the Christmas holidays.