The figure is down on the 153 cases reported in 2006; of those, 68 were robberies. Hong Kong police fear a rise in such crimes this month as many Hong Kong people cross the border to buy festive goods ahead of the Lunar New Year.

Police Superintendent Yu Chi-hung, an assistant commander in the border district, warned people to be extra vigilant when visiting the mainland.

Private cars used as unlicensed taxis offer lower fares and touts find customers at border checkpoints and bus and train stations.

'Victims have to surrender cash and valuables at knifepoint,' Mr Yu said. 'Some are forced to hand over their bank cards and PINs. They are freed once money has been withdrawn from their bank accounts.'

The factory manager robbed of nearly HK$200,000 was detained after he got into a Shenzhen-bound unlicensed taxi in Dongguan early on Christmas Day.

The driver had an accomplice hidden in the back of the seven-seater vehicle. Midway through the journey, the accomplice appeared and threatened the victim with a knife. The businessman was beaten up before being bound, gagged and blindfolded.

When he was given back his travel document and released, the man made his way back to Hong Kong and reported the crime to police at the border checkpoint.

Officers believe the number of robberies may be more than reported, as some victims might not want to make statements to police in Hong Kong or Shenzhen.

'In most of the cases, culprits returned identity cards and travel documents to victims. Sometimes, they also gave them money to get home,' Mr Yu said.

Police also expressed concern over a spate of crimes in which Hong Kong people had their money replaced by counterfeit banknotes by street vendors in Shenzhen.

'When victims present a 100 yuan bill, vendors tell that it is a fake note and hand back the bill,' Mr Yu said. 'In fact, vendors have switched the genuine note with a fake one. Their action is very fast.'

Dongmen in Shenzhen is considered a black spot for such crimes.