PHILADELPHIA/ZURICH - Kraft Foods Inc may raise its offer for Cadbury Plc or offer more cash in its bid if rival takeover offers emerge, a source familiar with the situation said on Sunday.

Kraft made a $16.8 billion hostile offer to acquire U.K. confectioner Cadbury, but rivals such as Hershey Co , Italy's Ferrero and Nestle now may be weighing takeover bids themselves, according to Reuters sources and media reports.

Kraft could keep its bid unchanged if no rival bidders emerged, however, the source said.

Kraft "made an offer to start the process," the source said, who declined to be named because they were not authorized to speak with the media. Kraft "never said that was its final offer," said the source.

Kraft could not be immediately reached for comment.

Cadbury has recently attracted greater takeover interest.

Swiss food giant Nestle may consider a bid for Britain's Cadbury to challenge a hostile 9.9 billion-pound bid by Kraft Foods Inc and a potential move by Hershey, Bloomberg reported on Sunday.

Nestle was still weighing its options and could decide against a bid, Bloomberg said, citing two unnamed people with knowledge of the matter.

Nestle declined to comment on Sunday.

Italian chocolate maker Ferrero and U.S.-based Hershey have teamed up and said on Wednesday they were reviewing a possible offer for Cadbury.

Italian newspaper Il Sole 24 Ore has reported that Hershey executives will go to Italy to hold a definitive meeting with Ferrero in the coming days.

Ferrero was not available for a comment.

Meanwhile, Cadbury's Chairman Roger Carr told the Sunday Telegraph his group would prefer a merger with U.S. chocolate maker Hershey rather than Kraft . But he added both bids could fail should they not be generous enough.

COMPETITION HEADACHE

Analysts had been viewing Nestle as a potential suitor for Cadbury. But such a deal may face some antitrust hurdles.

Nestle said in October it was likely to exercise its option beginning in January 2010 to sell its remaining 52 percent stake in Alcon, potentially raising up to $28 billion, so it could easily afford big buys.

The Swiss giant has declined to comment on Cadbury so far. It has said it does not plan any big acquisitions this year or next, but will focus on a strategy of "bolt-on" buys.

Due to competition issues, analysts had speculated that the Swiss company might consider a joint offer with U.S.-based Hershey Co, with the U.S. group seeking Cadbury's chocolate interests and leaving Nestle with the Trident chewing gum business.

But Nestle has been silent since Hershey and Italy's Ferrero said separately on Wednesday they were considering a bid.

Some market players have suggested Nestle could still help Hershey fund a bid by buying its U.S. license for the KitKat brand, potentially worth around $3 billion to $3.5 billion.

The Cadbury riddle is a difficult one to solve as virtually all players would face antitrust issues if they move, said an M&A expert who declined to be named.