(Add analyst forecast in paragraph 1 & 6, background in paragraph 2, results in paragraph 3 & 4, Britvic update in paragraph 7)

Jan 25 (Reuters) - British tonic maker Fevertree Drinks forecast annual core profit to fall short of market expectations, even as profit doubled in the second half on strong U.S. market performance, offsetting inflationary cost pressures in materials.

The company, which was founded in 2003, has been grappling with high glass costs in Britain ever since the Russia-Ukraine conflict pushed up energy costs, forcing it to initiate price increases to protect margins, while also ramp-up its glass production in the U.S.

The tonic maker on Thursday reported a 6% rise in total revenue for the year ended on Dec. 31, which included a 22% growth in the U.S., its largest market by revenue.

It said it currently expected a significant improvement in gross margin for 2024, underpinned by new glass contracts with fully hedged energy pricing and lower Trans-Atlantic freight rates.

The company, which manufacturers and sells drink mixers, said it now expected core profit for the year to be about 30 million pounds ($38.16 million), compared with its prior expectations of 30-36 million pounds.

Analysts on average expected core profit to be about 32.7 million pounds, according to a company provided consensus.

Separately, Britvic, a British soft drinks maker, said it witnessed strong trading during the Christmas season, aiding it to project full-year results to be in the range of market expectations. ($1 = 0.7861 pounds) (Reporting by Radhika Anilkumar in Bengaluru; Editing by Rashmi Aich)