Bollywood actress Sushmita Sen has given the thumbs down to Coca-Cola. The former Miss Universe has run into contractual problems with the soft drinks major, with her lawyers sending a legal notice to Coke.

Sen had been roped in last year to endorse Coke's largest brand Thums Up.

But the specific reasons for her slapping a legal notice on Coke could not be ascertained.

A Coca-Cola spokesperson said, "There are some contract problems with her (Sen). The legal department is currently reviewing the contract." However, Sen could not be contacted for comments.

It could not be ascertained whether Sen would continue to be associated with Thums Up. "It is too early for us to comment on this issue," another Coca-Cola executive added.

Apart from Sen, Coke had also roped in Bollywood macho man Salman Khan for the Thums Up campaign. Both the stars spearheaded the Thums Up -- Grow Up Challenge campaign.

The Thums Up campaign, Coca- Cola had claimed, resulted in a whopping 40 per cent increase in brand preference and a noticeable increase in market share last year. Sen, a Thums Up brand loyalist, was roped in for an astronomical sum by Coca-Cola.

In fact, it was the first time that a female star was signed by Thums Up and so Sushmita was the first woman on screen to say Thums Up -- Taste the Thunder!

With Salman Khan completely out of favour with Coca-Cola because of the recent incident where Khan was arrested for alleged drunken driving which killed one person and maimed three, the company roped in Khiladi star Akshay Kumar and model turned Bollywood actress Bipasha Basu for endorsing the Thums Up brand.

The Thums Up Challenge last year played the Pepsi-tastes-sweet card and tried to reposition Pepsi as a drink for children. The Challenge campaign trigerred off a series of television commercials by both the soft drinks majors. Pepsi and Coca-Cola took digs at each other and eventually they got entangled in a court battle.