With Chung posing as a customer and Monchu as his pet, they checked in at the venue, a pig farm that was converted into pet accommodation. Departmental officers later turned up and told the hotel owner he would be prosecuted.

'It was only because Monchu and I appeared to be close to each other that the operator let his guard down,' Chung said.

For her hard work, Monchu was rewarded yesterday when she won an outstanding service award at Animals Asia Foundation's Dog Devotion Awards in Tsuen Wan.

The golden retriever joined the government team five years ago when her owner had to relinquish her because she moved to a public housing estate that banned pets.

Now retired from undercover work, Monchu keeps other abandoned dogs company at animal centres. 'When we check the dogs to see if they are suitable for adoption, Monchu tries to calm their nerves,' Chung said.

Another dedicated dog honoured yesterday was Coby, a female Labrador who works for the police. Last year, the eight-year-old helped authorities locate a mother who dumped her newborn baby in a rubbish bin.

'She sniffed the bag which contained the baby and tracked the blood dripping from it,' dog handler Ip Kwok-wing said. 'After searching along many flights of stairs, she led us to the mother who lived on the 17th floor [of an apartment].'

Recently, the tracker dog found 1.2kg of ketamine worth HK$140,000. Coby also helped save an elderly person with dementia who wandered from home and fell into a river.

Police say Coby's sniffing skill is honed through weekly practice. 'Officers walk along a route and leave something and then she has to retrace the route an hour later and locate the object,' Ip said.