The National Crime Agency (NCA) has seized more than £38 million worth of heroin hidden in pomegranate juice bottles.
The Class A drug weighed 388 kilos.
It was found in a ship container at the port in Southampton.
Three suspects were caught as they began to unload the container which contained 2.6 tonnes of pomegranate juice at an industrial premises in north east Birmingham.
The bottles of purple juice turned red if they held heroin.
A fourth man was arrested at a residential address in Alum Rock, Birmingham.
The four suspects were released on bail.
Derek Evans, NCA branch commander, said:
“The Class A drug trade is a scourge to society and this seizure goes a significant way to helping to protect the public.
“Drugs are inextricably linked with organised crime groups and the use of serious violence which can often spill over wrecking the lives of innocent victims and their families.
“The NCA works at home and abroad to do everything it can to stop heroin coming into the UK and damaging our communities.”
