y Hilton owner Blackstone?Group, the world’s largest buyout company, for a reported £600 million.

Blackstone has agreed to buy City Inn, the owner and operator of the eight-hotel chain, from the group’s founders and Lloyds’s property investment unit Uberior Ventures, Mint Hotels said in a statement.

City Inn owns seven Mint hotels in the UK and opened its eighth in Amsterdam in May, racking up net debt that totalled £417 million at the end of March, it said in a filing.

Blackstone’s Hilton International chain will reposition the Mint hotels within its DoubleTree by Hilton and Hilton Garden Inn brands. Hilton is seeking to add 100 more hotels to its network through 2014.

Mint Hotels has been the chain's brand name since November?when it?changed from?City Inn, the chain father and son Sandy and David Orr founded with Donald McDonald and Bill Crerar in 1995.

The company became the first venture with Bank of Scotland’s property investment arm three years later, which was subsequently absorbed by Lloyds in its takeover of HBOS in