Meat from a third cow bred using a cloned animal has gone into the UK food chain, officials said today.

The news came as evidence emerged that some clone-derived beef had also been exported.

Amid continued confusion over the legality of the practice, the Food Standards Agency said meat from the third animal, a bull calf, was sold in London last month. Last week it revealed that meat from two slaughtered bulls had been sold elsewhere.

However, agency investigators checking reports that milk from animals bred using embryos of a cloned US prize-winning cow was sold have been told by farmers that this had not happened.

The FSA has identified eight animals born from embryos of the original cow cloned in the US – four bulls and four cows. All are Holsteins, which are usually bred for dairy production.

Five are known to have had offspring of their own, and although these would usually be considered too young for selling as meat, the FSA said one male calf was slaughtered at less than a month old in June and its meat sold at a London butchers.

Food from the first animal, slaughtered last year, was sold by four butchers in Scotland and one in north-east England.

Meat from the second animal, killed in May, went to Belgium. The Belgian authorities have been informed.

The FSA said: "While there is no evidence that consuming products from healthy clones, or their offspring, poses a food safety risk, meat and products from clones and their offspring are considered novel foods and would therefore need to be authorised before being placed on the market." Those who break the rules face fines of up to £5,000.

The agency, which is considering whether to release further details, said "some of those involved in the investigation were not aware, and could not reasonably be expected to have been aware, that the animals in question were the offspring of clones".

The investigations began after a US newspaper printed unverified allegations that clone-derived milk had been sold.

The FSA believes this is illegal under EU legislation about novel foods, but the European Commission claims these rules do not cover meat or milk from cloned offspring.

The organisation has suggested there could be "lots" of milk from cloned animals being sold across Europe.

There seems no way of knowing whether there has been other such food traded in the EU. The commission is expected to urgently discuss the issue later this year, following MEPs' call to ban such food from being sold.

Food bred from clones is legally sold in the US.

Prosecution in Britain would be the responsibility of local council trading standards officials. Only one farm, near Nairn, in Inverness, has so far been publicly named in the investigation.