Environmental campaigners dressed up as cows and chained themselves to the dairy aisle of a Swansea supermarket in a protest over GM milk.
Greenpeace protesters in Swansea are captured on the activists' video
Greenpeace had targeted the Sainsbury's store, claiming that its own-brand milk comes from cows fed on imported GM animal feed.
Sainsbury's said it was "disappointed" by the action and denied that its milk contains GM materials.
Last month Greenpeace activists boarded a ship carrying GM maize off the south Wales coast.
South Wales Police say there were no arrests in the protest which ended later on Saturday at the store in Quay parade.
More than a dozen costume cows had been "released" in the store, while other protesters chained themselves to the dairy aisle.
A spokesman for Greenpeace said the supermarket chain's own-brand milk comes from cows fed on imported GM animal feed.
But this claim was denied by the supermarket.
"We are disappointed that Greenpeace has chosen to target Sainsbury's when
this is clearly an issue for the whole food industry," said a company statement.
"Customers can be assured that our milk does not contain GM materials and is sourced from the
same farms that supply other supermarkets, like Tesco and Asda, as well as hotels, schools and hospitals.
"To offer our customers choice we have launched
a milk from cows fed on animal feed guaranteed to be free from GM."
The statement added that Sainsbury's have met with Greenpeace but said the group did "not seem to appreciate that this
issue cannot be tackled by a single retailer in isolation".
It went on that the action "serves only to confuse
consumers rather than inform them."
It also said its "selected farm semi skimmed fresh pasteurised milk" is not
available in the Swansea store.
The milk is being trialled in 105 stores in London, the south east and south west of England.
Greenpeace said around 500 customers signed letters of protest which were handed to the store manager.
Last month, 13 Greenpeace protesters were remanded after illegally boarding a ship carrying GM crops in the Bristol Channel.
They denied causing a public nuisance and conduct endangering a ship's structures or individuals before magistrates in Barry.
The freighter the MV Etoile was boarded last month in the Bristol Channel to prevent it unloading GM animal feed.