Food safety officials are investigating a possible link between seeds sold by a British firm and an E coli outbreak in France.

The action by the Food Standards Agency (FSA) comes after France banned the sale of three types of seeds linked to Thompson & Morgan, based in Ipswich, Suffolk.

Eight people affected by E coli have been admitted to hospital in Bordeaux. French officials said the results of tests on two of them showed an infection of the same strain of E coli that killed 44 people and affected 3,700 others, including Britons, in an outbreak centred on Germany.

An investigation by France's competition, consumption and fraud prevention agency found those hospitalised had consumed rocket and mustard vegetable sprouts believed to have been grown from seeds sold by Thompson & Morgan at a school fair in the south-western town of Begles.

Commerce minister Frederic Lefebvre said the ban involved fenugreek, mustard and rocket seeds.

But he added: "The link between the symptoms and eating of the sprouts so far has not been definitively established."

The FSA said it was asking Thompson & Morgan for more information about the seeds. It added that no E coli cases had been reported in the UK.

The agency said in a statement: "We have been in contact with the French authorities about this outbreak and are aware that a UK business has been named in connection with it.

"We have asked for further information from the French authorities with regard to the three named type of seeds to help us carry out investigations in the UK."

It was possible for seeds to carry E coli but the investigation must find out how the seeds were grown, who planted them and how the food was prepared, the FSA said.

The agency added that it was revising its guidance on the consumption of sprouted seeds such as alfalfa, beansprouts and fenugreek in light of the French outbreak.

"As a precaution the agency is advising that sprouted seeds should only be eaten if they have been cooked thoroughly until steaming hot throughout – they should not be eaten raw.

"The agency also advises that equipment which has been used for sprouting seeds should be cleaned thoroughly after use. You should always wash your hands after handling seeds intended for planting or sprouting."

Thompson & Morgan's website describes it as an expert in the garden since 1855.

There is no suggestion of a link to the German E coli outbreak.

Thompson & Morgan told the BBC it sold "thousands of packets and had no reported problems".

"It is highly unlikely to be the seeds themselves but the way that they were used and handled," the company said in a statement.

Managing director Paul Hansord said the firm bought its seeds in bulk from suppliers around the world and those under investigation may have come from Italy.