TOKYO - A STRING of taxi driver killings and other attacks in central Japan is being investigated by police, as cab companies in the normally safe country install shields and cameras to protect drivers from being slashed.

Two drivers were stabbed to death while three others were slashed and injured - all in the space of about a week in and around Osaka, police said.

'We didn't have cases like this before,' said a spokesman at Osaka Prefectural police. 'There is a possibility that the perpetrators are the same, or that these are copycat criminals.' A 23-year-old man was arrested on Tuesday on suspicion of wounding a taxi driver with a paper cutter, the spokesman said.

The other cases were still under investigation.

Taxi companies are responding by installing partitions and surveillance cameras in cabs, an industry spokesman said.

'The perpetrators are choosing taxi drivers, who work under harsh labour conditions in closed space, following the orders from customers. It is totally unacceptable,' said Nobuo Shimizu of Hyogoken Taxi Kyokai, a taxi association in the region.

Japan, proud of its relatively low crime rate, has been shocked by a series of stabbing rampages in the recent years, sparking talk of failing communities and declining morality. -- Reuters