Grace is one of two elite sniffer dogs the Correctional Services Department has trained under a new programme started last year, the first of its kind in Southeast Asia.

'Grace maintains a very sharp olfaction [sense of smell], a prerequisite for the new mission,' said the head of the department's dog unit, Wong Yu-chiu. Two more English springer spaniels would be trained in the coming months, he said.

Officers confiscated only six mobile phones between 2006 and 2008. While the problem of smuggled phones was still relatively small, the department was taking preventive measures after learning that this is becoming a serious issue in overseas institutions, a department spokesman said

Meanwhile, the department was also seeking to improve its dog breeds by importing guard dogs and sniffer dogs from the mainland for the first time last year, said Mr Wong.

'Inbreeding appears to be a problem among our dogs, and we need to introduce dogs from new sources,' he said, adding that the mainland training bases were providing dogs much more cheaply than they could be sourced locally.

Five German shepherds were imported from Shenyang as guard dogs, while six sniffer dogs, including a German shepherd, three Labrador retrievers and two English springer spaniels, also arrived to the city from Nanjing last year.

The dog unit now has 57 dogs, 10 of which are still puppies.

Nose knows

Dogs have more than 220 million olfactory receptors, compared with a human's 5 million

Their sense of smell is believed to exceed ours by a factor up to: 100,000