Bullock, Tatum bonded while filming 'The Lost City'

STORY: "We're very similar, oddly," Bullock said of Tatum, as they premiered the film in London on Thursday.

"We discovered that and it confused us. It was a little perplexing as to why are we so similar. But our sense of humour is just very sophomoric and we take care of each other," Bullock, who also produced the movie, told Reuters.

"She's like my sister. We're like siblings. We have a whole backstory that we were created in a petri dish together and they put her out first to see how she was going to do. And then once she survived, they put me out. We were just separated at birth, really," said Tatum.

The romantic comedy adventure stars Bullock as Loretta Sage, a successful novelist who becomes a recluse after her husband's untimely death. Persuaded by her publicist to embark on a press tour to promote her latest book with her handsome cover model Alan (Tatum), life starts to imitate her art when an eccentric billionaire, played by Daniel Radcliffe, kidnaps Sage, convinced she can lead him to an ancient treasure he believes is buried on a tropical island.

Alan springs into action to rescue Sage, helped by his mysterious acquaintance Jack Trainer (Brad Pitt) and a high-adrenaline escape through the jungle ensues.