By Will Butcher

West Ham chiefs have launched an investigation into the £6.2million transfer of Olympiakos left-back Arthur Masuaku, according to a report.

An investigator was given a mandate last week to find out if the Hammers have overpaid the Greek champions by £1million, as senior officials try to fathom if someone has been paid but not been named on the official transfer document.

The Daily Mail has claimed that chairman David Sullivan and club secretary Andrew Pincher have given an investigator instructions to find out if the former France Under-19 international’s transfer fee was larger than it needed to be.

The Hammers’ board want to make sure that there are no loose ends on either side of the deal, as they look to operate the club cleanly and professionally.

Corruption is rife in Greek football currently right up to the top level, with Olympiakos chairman Vangelis Marinakis also under investigation as part of a match-fixing probe.

The former Valenciennes left-back is one of eleven new faces at the London Stadium this summer after signing a four year contract in East London.

The pacy full-back was brought in as a replacement for first-choice defender Aaron Cresswell, who was ruled out for four months with a knee injury during pre season.

At just 22, Masuaku has 107 career appearances already as well as 12 Champions League appearances during his time with Olympiakos. The defender has hit the ground running with the Hammers, making four appearances.

In other West Ham news, this winger has won award for his impressive performances this season.