FILE PHOTO: People shop at a grocery market, in London, Britain May 6, 2023. REUTERS/Emilie Madi/File Photo

LONDON (Reuters) -Britons became more gloomy this month and the prospect of tax increases in finance minister Rachel Reeves' budget in November threatens to damage confidence levels further, a survey showed on Friday.

Market research firm GfK said its consumer confidence index sank to -19 in September from -17 in August which had been its highest since December, and slightly below the -18 forecast in a Reuters poll.

Neil Bellamy, consumer insights director at GfK, said all five measures of confidence dipped this month and a separate gauge of savings intention fell sharply.

An index measuring sentiment about the economic outlook now stands at -32, way down from -11 in June last year, shortly before Prime Minister Keir Starmer's Labour Party won a parliamentary election.

"With tax rises expected in the November budget, the risk is that confidence inevitably falls," Bellamy said.

Reeves is expected to raise taxes in her annual fiscal statement on November 26 in order to remain on course to meet her budget targets, having ordered employers to pay higher social security contributions in October last year.

The GfK survey was based on a poll of 2,003 individuals conducted between September 1 and September 11.

(Writing by William Schomberg; editing by Suban Abdulla)