Real estate mogul Donald Trump is facing a $4 billion (GBP2 billion) lawsuit from a Las Vegas property management company after he was accused of monopolising the market in the city. The Apprentice star is alleged to have unfairly blocked property firm Nights at Vegas from leasing out a number of the condominiums in the Trump International Hotel + Tower. Nights at Vegas takes a 20 per cent cut of the rental income when it leases out an apartment in the complex, while Trump owns a management company that takes 50 per cent of the lease income. But bosses at Nights at Vegas claim Trump has banned them from conducting business using the name Trump in any of its advertising or marketing in relation to the condos at the Trump International - making promotion of the properties virtually impossible for the firm, reports TMZ.com. Nights at Vegas is suing on the grounds of violation of anti-trust laws, declaratory relief for non-infringement of trademark, false promotion and unfair competition. The company is seeking $1 billion (GBP500 million) in compensation, with another $3 billion (GBP1.5 million) in punitive damages.