* Kraft sees low initial acceptance for Cadbury offer
*Investors set to wait to see if Kraft raises bid
* Analysts say Kraft needs to increase bid above 800p/share
* Cadbury shares down 0.8 percent to 773 pence
(Rewrites with analyst comments, details, updates shares)
LONDON, Jan 6 - Kraft (KFT.N) said it had a 1.52 percent take-up from Cadbury (CBRY.L) shareholders for its 10.5 billion pound ($16.8 billion) hostile bid, with analysts saying the U.S. food group will have to raise its offer to win.
Kraft said on Wednesday it had received the acceptances by its first closing date of 1300 GMT on Jan. 5 and its offer remained open until Feb. 2.
Most investors will likely be waiting until a Jan. 19 deadline for Kraft to raise its bid before deciding whether to accept, with analysts saying a price over 800 pence per share would be needed for Kraft to succeed.
Kraft's cash and shares bid is currently worth 765 pence per Cadbury share or 10.5 billion pounds ($16.8 billion), against a current share price down 0.8 percent at 773 pence by 1020 GMT.
Kraft will have to offer at least 810 pence to attract acceptances from current Cadbury shareholders, said analyst Dirk Van Vlaanderen at Jefferies International.
Martin Dolan at Execution Research said Kraft will have to offer over 800 pence to encourage Cadbury to let it see its books and believes Kraft could pay an extra 60 pence per share.
On Tuesday, a warning by Kraft's biggest shareholder, Warren Buffett, and Swiss food group Nestle's (NESN.VX) announcement it would not make a rival bid pushed Cadbury shares lower and Kraft stock higher.
Buffett said he would vote against Kraft's proposal to issue 370 million new Kraft shares to fund its Cadbury bid unless he was convinced it did not destroy shareholder value.
Buffett's intervention and Nestle's decision has narrowed the premium of Cadbury's share price to the bid price to around 1 percent from nearly 10 percent on Monday.
Under Britain's takeover rules, Kraft has until Jan. 19 to raise its bid while Cadbury shareholders have until Feb. 2 to accept.
Potential bidders for Cadbury who have expressed an interest publically, Hershey (HSY.N) and Italy's Ferrero, have until Jan. 23 to come up with fully financed bids or withdraw. (Reporting by David Jones; Editing by Dan Lalor) ($1 = 0.6267 pound)