One person has died linked to the E. coli outbreak which experts believe has been spread via lettuce leaves.

The UK Health Security Agency (UKHSA) said it had identified two people in England who died within 28 days of infection with shiga toxin-producing E.coli (Stec).

“Based on the information available from health service clinicians one of these deaths is likely linked to their Stec infection,” it said.

“Both individuals had underlying medical conditions. The deaths occurred in May.”

As of June 25, there have been a further 19 cases of Stec, bringing the total number of confirmed cases to 275 in the UK.

READ MORE: E.coli outbreak: Symptoms , what is it, & how to reduce risk

A number of food manufacturers have recalled sandwiches, wraps and salads sold in major supermarkets and retail chains over fears they are linked to the outbreak.

The Food Standards Agency (FSA) has said lettuce used in the products are thought to be the likely source of the outbreak.

The UKHSA said the number of cases it is seeing is declining, but more will come to light as further samples are referred from NHS laboratories.

So far, there have been 182 cases in England, 58 in Scotland, 31 in Wales and four in Northern Ireland. The latter cases are thought to have acquired their infection in England.

At least 122 people have been admitted to hospital for treatment since the start of the outbreak.

Darren Whitby, head of incidents at the FSA, said: “Earlier this month, we confirmed that several sandwich manufacturers had taken precautionary action to withdraw and recall various sandwiches, wraps, subs and rolls after food chain and epidemiological links enabled us to narrow down a wide range of foods to a type of lettuce used in sandwich products as the likely cause of the outbreak.

“This remains a complex investigation and we continue to work with the relevant businesses and the local authorities to ensure necessary steps are being taken to protect consumers.

“Although we are confident in the likely source of the outbreak being linked to lettuce, work continues to confirm this and identify the root cause of the outbreak with the growers, suppliers and manufacturers so that actions can be taken to prevent a re-occurrence.”