DETECTIVES leading the hunt for a herbal doctor who fled to China after being charged with a sex offence yesterday admitted it was "like trying to find a needle in a haystack".

An international manhunt was launched after Dr Gu Zu Sun, a leading Chinese herbalist, went into hiding after being charged with a sex offence at his Darlington practice last year.

Dr Sun, a former consultant at the Dr and Herbs treatment centre in the Cornmill Centre, is believed to be staying in the Far East.

He is accused of sexually assaulting a male patient during an acupuncture and massage session. Since then, another patient - a 51-year-old businessman - has made similar allegations against the herbalist, who is a leading medicinal specialist in China.

Dr Sun denied the charge at an initial appearance at South Durham Magistrates' Court in October, but a warrant without bail was issued for his arrest after he missed a subsequent appearance.

Police received information from a reader of The Northern Echo in May as to Dr Sun's possible whereabouts, but despite liaisons with Chinese authorities and Interpol, a breakthrough has yet to be made.

Yesterday, Detective Sergeant Dave Wilkes, of Darlington CID, said the investigation was ongoing, but was proving to be a slow process.

"As far as we know he is still in China and we are trying to and track him down," he said. "But really, it's a needle in a haystack and out of the 20 billion or so people who live in China, it's proving very hard to make a breakthrough.

"But we are still liaising with Chinese authorities to see if we can get him picked up.

"He is still very much wanted by police and the court, and the warrant is still outstanding. The crime will never go away however long it takes, and he will continue to be a wanted man."

Former colleagues at the Dr and Herbs practice said they were aware he was in China, but have had no contact with him since he left. Anyone with information about Dr Sun or his whereabouts can contact police on 0845 60 60 365.