West Ham are "very close" to being bought by former Birmingham City owners David Gold and David Sullivan, BBC Sport understands. Lotus F1 chief Tony Fernandes, thought to be the duo's main rival, pulled out of the race on Monday evening. Finance firm Intermarket and Italian Massimo Cellino are the other known interested parties. "Gold and Sullivan are the real front-runners now," said 5 live's senior football reporter Ian Dennis. "At one stage or another they've all been touted as being favourites to take over at West Ham but I understand that Gold and Sullivan are very, very close now to moving in. "It will be a relief, not only to the supporters but also to [manager] Gianfranco Zola, so that they can now concentrate on on-the-field matters." The club are currently owned by CB Holding, which has indicated West Ham are £38m in debt. The main shareholder in CB Holding is Icelandic bank Straumur, which has previously said it was in no hurry to sell the club - although that was before the various bidders became known. At one stage Fernandes was seen as the favourite to take over but admitted defeat on Monday evening when he told his Twitter feed: "Deal lost on West Ham. Hopefully new owners protect what's good. We gave awesome deal and new ideas to rejuvenate a club and bring excitement." West Ham have effectively suspended any activity in the January transfer window until the takeover situation is resolved. Dennis added: "My understanding is that they don't have to sell in the transfer window. There have been rumours about Scott Parker maybe moving on but if the takeover happens sooner rather than later I don't think there will be any departures from Upton Park." Hammers boss Zola, whose future may hinge on which bid wins, acknowledged the situation was frustrating. "These players, this team, they deserve to be helped. Stability for the club would be massive," he said after a 0-0 draw at Aston Villa on Sunday lifted his side out of the Premier League relegation zone. "Right now we can't do anything we just have to wait for something to happen with the club. Once we know where the club is going, then we have a chance." The interested parties: David Gold/David Sullivan - Former Birmingham City owners have been determined suitors of the Hammers for several months. They once held shares in the club and boast the liquid assets required. Intermarket - Finance firm based in London's Canary Wharf, made money with the FX currency exchange business. Ex-West Ham striker Tony Cottee is an adviser but chief executive Jim Bowe died in America earlier in January. Massimo Cellino - The president of Serie A club Cagilari emerged as a potential late bidder last week and there were even reports in Italy he had secured a deal but these proved premature. The pair guided West Ham to ninth in the table after a sticky start. West Ham are currently 16th in a season that has been plagued by injuries and off-the-field distractions.Former Chelsea favourite Zola, and assistant Steve Clarke, took the managerial reins at West Ham in September 2008 after Alan Curbishley's departure. "I know I can do this job but you always have to prove yourself every day," said Zola on Friday. "I am not going to go to anyone and say 'look, I am doing well'. The results do the talking. If what I am doing is not good enough on the pitch it is right they change." BBC