Six men, including four from Bradford, have been jailed for a total of 109 years for their part in a sophisticated plot which saw heroin worth more than £9 million smuggled into the UK in bottles of baby powder sent through the post.

Jailing the six yesterday at Leeds Crown Court for 19 to 25 years Judge Christopher Batty said heroin brought misery to thousands of people.

He said: “Heroin is a highly dangerous addictive substance. People who peddle it can expect long sentences, those who import it and flood the streets of this country with it can expect to go to prison for even longer.”

During a ten-week trial the jury heard how parcels were sent from post offices in Bradford to Pakistan using a recorded or tracked service.

Once they arrived accomplices there opened them and replaced the contents with plastic bottles of Johnson’s baby powder made in Thailand, which had heroin packages inserted inside.

The parcels were resealed and sent back to addresses in Hull and later in Manchester marked “undelivered – return to sender” or similar words, said Jonathan Sandiford prosecuting.

The jury heard the smuggling came to light in 2011 after staff at the Royal Mail Citadel Park delivery office in Hull became suspicious at the number of such parcels arriving there.

Five were intercepted and found to contain an average of 1.9 kilogrammes of heroin, the overall total of 9.460 kilogrammes had a street value of £473,000.

Police identified from records that a further 94 packages had been delivered which with a similar content meant a street value of £8.93 million. They had been posted from 12 different post offices in Bradford.

Jailing Khalid Mahmood, 30, of Low Lane, Clayton, Bradford for 25 years, Judge Batty said he was satisfied he had played a leading role in the conspiracies concerned.

The court heard Mahmood was jailed for 51 months in 2002 for his part in the Bradford Riots and received four years in June 2008 for involvement with a firearm. Fiaz Ahmed, 31, of Cambridge Street, Oldham, was jailed for 23 years after he was described as playing a leading role in the operation, dealing with the heroin once it arrived in the UK.

Faisal Khan, 30 of Burnett Avenue, Marshfields, Bradford was jailed for 21 years after the judge described him as Mahmood’s trusted ally having made at least two trips to Pakistan.

The judge said Yasser Uddin, 31, of Clifton Villas, Manningham, was a postman and trusted friend of Mahmood, who used his knowledge of the Royal Mail system to keep tabs on the packages. He was jailed for 21 years.

Usman Bari, of Middleton Court, Hull, was jailed for 19 years. The judge said he had been the “eyes and ears” at the Hull end of the operation.

All five were found guilty by the jury of conspiracy to import class A drugs, conspiracy to supply and conspiracy to launder the proceeds.

A sixth man, Mahmood’s brother Azhar, 28 of Upper Kipling Close, Bradford who was convicted on a money laundering charge was given a ten-month jail sentence suspended for two years and ordered to do 200 hours unpaid work. The court heard he was under surveillance when he went to Leicester and collected £38,000 in cash.

Detective Inspector Gary Curnow, from the Regional Organised Crime Unit said: “This crime group based in Bradford were involved in the international trafficking of class A drugs. Their imprisonment demonstrates the priority and success that forces' in the Yorkshire and Humber region, alongside partners including the Border Force, are having in terms of tackling those involved in the higher echelons of the drugs trade.”

Phillip Holliday, of Border Force, said: “This case shows how our officers work closely with the police and others to stop people smuggling Class A drugs into the UK.

“Border Force is at the forefront of the fight against the drugs trade which can have such a destructive impact on individuals and communities.”