Hain's Estonian accomplice, Sergei Petrenko, received a sentence of three years and eight months in prison.
Prosecutors had asked that Hain, 43, of Bathgate, Scotland, be sentenced to three years and Petrenko, 42, be sentenced to five years. Hain pleaded guilty in the trial which started in September, whereas Petrenko denied any guilt.
Hain told the court he was offered £20,000 ($29,000) to take part in the smuggling by his friends Robert Bruce Wright, 35, and Leslie Brown, 45. The two are known as underworld figures in Scotland and are currently under arrest awaiting extradition to Estonia.
Petrenko claimed he took a job with Wright performing routine tasks for a monthly fee of 7,000 kroons ($400) about four months before his arrest. He said he didn't know about the drugs as he understood English very poorly.
Estonian national security police arrested Hain and Petrenko in Tallinn's passenger port on Nov. 2, 2000 as they were boarding a ferry bound for Finland. They found 19.4 kilograms of opium stashed in their car. According to Scottish drug experts, the opium would have yielded 6.5 kilograms of heroin, worth some £1 million in street prices in Scotland.
Hain and Petrenko's arrest followed a police operation which took place over several months and involved British law enforcement agencies. According to the police, Wright and Brown were attempting to establish a route for the smuggling of drugs from Asia to Britain via Estonia.