Police today renewed their appeal for information in the hunt for Charlotte Church's ex-boyfriend as an alleged associate was jailed for 10 years for his part in a £10m heroin haul.

Kyle Jason Johnson, 24, who dated the millionaire singer for 18 months, is suspected of supplying high-grade drugs from a safe house in east London.

He has not been seen since detectives swooped on the three-bed property in Meath Road, Forest Gate, in December last year.

It is thought to have been the base for a drugs ring who were ready to flood the capital with heroin in the run-up to Christmas.

Johnson had been living in the Stratford area but the police have widened the search to his hometown of Cardiff and also Nottingham.

Officers from the Met's Central Task Force found 149-kilos of heroin split in to 597 envelopes and stashed in cardboard boxes when they raided the safe house.

The drugs were up to 65% pure and estimated to have a street value of £9.956m.

Johson's alleged associate, 20-year-old Calvin Markall was arrested on 4 December after he was seen locking up and leaving the property by surveillance teams.

He was arrested and charged with possession of class A drugs with intent to supply.

Markall pleaded guilty and was jailed for 10 years yesterday (wed) at Inner London Crown Court.

Detective Inspector Colin Stephenson said: “This was one of the most significant drugs seizures by the Met last year, and has seriously disrupted a major criminal network planning to flood London with heroin over the Christmas period.

“The fact that Calvin Markall pleaded guilty demonstrates the thoroughness of the investigation we conducted and the overwhelming evidence we obtained.

“Today's sentencing is yet another blow to those who attempt to supply drugs in London.”

Johnson split from the “voice of an angel” star in 2005. He later sold a kiss and tell exclusive about their love life to a tabloid Sunday newspaper.

Church, now 23, was a schoolgirl sensation with her pure classical voice and sang for the Pope, Presidents and Royalty.

After selling 10.5 million albums she switched to pop music and relaunched herself with considerably less success as a singer-songwriter, actress and TV chat show presenter.

She plans to marry long-term boyfriend Welsh rugby union international Gavin Henson, with whom she has two children.

Police say Johnson is 6ft 1in tall, with short shaved black hair and has a Welsh accent.

Anyone with information should call 020 8345 0050 or Crimestoppers on 0800 555 111.

Calvin Markall, of Rumney, Cardiff, had pleaded guilty to possession with intent to supply in April 2009.