Former American first daughter Chelsea Clinton has sparked speculation her relationship with IAN KLAUS is over - after she was spotted partying with another man.

The two, who met at Britain's prestigious OXFORD UNIVERSITY, haven't been seen in public for quite some time, and although Clinton says they're still together, American website PAGE SIX reports she's been spending a lot of time with tuna heir EVAN METROPLOUS.

But there's a huge problem - Evan already has a girlfriend.

A source tells the site, "I work with Evan's girlfriend, ELENA RUSSELL.

"She is upset that he's been hanging out with Chelsea so much. She feels like there's something going on between the two since they talk a lot on the phone."