Health bosses have revealed what they believe caused more than 40 suspected salmonella cases linked to a Watford restaurant.

A food poisoning probe, led by the UK Health Security Agency (UKHSA), was launched when numerous people reported falling ill after eating food from Taste of Lahore between March 22 and April 1.

There were subsequently 25 laboratory-confirmed cases of salmonella and 18 “probable” cases – symptomatic individuals who did not provide a sample for lab testing.

The investigation into specifically what caused the illnesses has been ongoing, and the UKHSA has this week confirmed: “We suspect that it is linked to a poultry product and have informed the Food Standards Agency, which is responsible for the next steps of the outbreak investigation.”

Sarah Weir, of UKHSA East, added: “We are confident that there is no ongoing public health risk related to the restaurant and believe this was an isolated incident. No further cases among diners have been found since the initial reports of illness.”

The Food Standards Agency told the Watford Observer that the salmonella cases “may be linked to eggs imported from Poland”.

“We are looking into the source of the outbreak and will not hesitate to take any necessary action to keep UK consumers safe,” said Tina Potter, head of incidents at the FSA.

An FSA spokesperson also confirmed there were cases linked to a second restaurant in Milton Keynes and shops in Blackburn.

The Watford Observer understands there is believed to be one case linked to the restaurant and two to the shops.

Taste of Lahore in High Street was contacted for comment.

In May, Environmental Health staff visited the premises and found hygiene standards and food preparation methods “all appear satisfactory”, the UKHSA said that month.

“They are continuing to work with the management of the restaurant to determine a possible source – including investigating the supply chain,” it added at the time.

In early April, three people who claim not to know each other separately told the Watford Observer they needed hospital treatment after eating food from the restaurant on Wednesday, March 29.

One claimed they became so ill they thought they were going to die, while another said they vomited over a hundred times during four “traumatic days”.