The UK competition watchdog has decided not to refer William Hill's agreement to buy 624 betting shops from rival Stanley Leisure - owner of Birmingham's Star City casino - to the Competition Commission for detailed scrutiny.

Yesterday's announcement from the Office of Fair Trade came after William Hill gave a commitment to take measures to alleviate potential regulatory concerns. It has given undertakings to sell around 50 sites, which will leave it with 546 Stanleybet outlets.

"The Office of Fair Trade is not referring the completed acquisition to the Competition Commission because it is considering whether, instead of making a reference, to accept appropriate undertakings from William Hill," the OFT said in a statement.

William Hill in May agreed to buy Stanley's estate of betting shops for £504 million, in a deal which saw it leapfrog Hilton Group's Ladbrokes business to become the country's biggest bookmaker.

The deal puts William Hill into areas where it is relatively underrepresented.