LONDON (Reuters) - One person has died in Britain linked to an ongoing E. coli outbreak, the UK Health Security Agency said on Thursday, with the total number of confirmed cases rising to 275.

UKHSA said it had identified two individuals in England, both of whom had underlying medical conditions, who died last month within 28 days of infection with the Shiga toxin-producing E. coli, or STEC, strain of the bacteria.

One of those deaths was likely linked to their STEC infection it said, based on information available from clinicians.

UKHSA first flagged a rise in STEC cases on June 6, and all the currently confirmed cases had symptom onset dates before June 4. Symptoms include severe and sometimes bloody diarrhoea, stomach cramps, vomiting and fever.

"Although case reporting rates are declining, we expect to see more cases linked to this outbreak as further samples are referred to us from NHS laboratories and whole genome sequencing is conducted," UKHSA Incident Director Amy Douglas said in a statement.

Several sandwich manufacturers have withdrawn or recalled various sandwiches, wraps, subs and rolls as a precaution after the Food Standards Agency narrowed down the likely source of the outbreak to a type of lettuce.

(Reporting by Muvija M, Editing by Kylie MacLellan)