West Ham co-owner David Gold has rubbished claims Jack Collison will leave this summer after the midfielder was linked to West Brom and Stoke.[LNB] The Premier League pair were rumoured to be in the hunt for Collison's signature - but the 22-year-old revealed at the end of last season he would happily stay and fight for promotion.[LNB]Gold confirmed the Upton Park club were not obliged to sell one of their prized assets, saying: "Jack Collison is not for sale.[LNB]"I am with DS (co-owner David Sullivan) as we speak and I can promise that he and Sam (Allardyce) are working on new signings 24 hours a day."[LNB]Collison, who missed out on much of last season's fight against relegation because of injury, is under contract until 2013.