SIX men are in custody today after customs officers foiled a plot to smuggle one of the biggest heroin consignments ever into the UK through Felixstowe.

SIX men are in custody today after customs officers foiled a plot to smuggle one of the biggest heroin consignments ever into the UK through Felixstowe.

Around 400 kilos of the opiate, with a street value believed to be in excess of £30m, were discovered among a cargo of cat litter at the Suffolk port.

Although customs officers are remaining tight-lipped about the seizure for operational reasons, the value of the drugs would indicate it was a very high grade of heroin.

An international drug cartel from Europe are thought to be behind the attempted importation which was smashed in a joint operation by local and national customs officers, along with members of the National Crime Squad.

It has not been revealed where the ship the containers were on docked from. However countries such as Turkey and, Istanbul in particular, are known to be at the centre of the heroin trade.

The men who are currently remanded in custody appeared at Horseferry Road Magistrates Court in London yesterday.

Amid tight police security they were charged with the illegal importation of heroin between January 1 and June 5 this year.

It is believed the men were arrested in London, Wales and at Luton Airport on Wednesday. None of them are from Suffolk.

The cargo of heroin was discovered at the Port of Felixstowe on May 23.

HM Customs would not confirm how it the drugs were found but it is known that Felixstowe is one of the ports which has a large sophisticated scanner that is specifically designed to identify drugs disguised by cover loads in containers.

As the seizure was in May, but the charges relate to importation during the first six months of the year, those under arrest could be thought to be responsible for other consignments.

The heroin found at Felixstowe may have only be hidden in one or two of the batch of containers which housed the 160 tons of cat litter used to cover the illegal load.

A London-based customs spokesman today confirmed it had been involved in an operation with the National Crime Squad in which a seizure had been made. However he would not confirm whether drugs were involved or divulge any further details.

"For operational reasons, I can not go into further details at this stage," he said.

N The scourge of heroin. Special report see page 6.