TOKYO, JAPAN - A JAPANESE hospital said on Friday it has launched an investigation after six people died of infection with an incurable bacteria, a hospital official said on Friday.

Thirteen people treated at the emergency room of Sapporo Medical University Hospital were found since 2006 to have contracted multi-drug resistant Pseudomonas Aeruginosa, the official said.

Six of them died of the bacterial infection, but it is not known yet if they contracted the bacteria at the hospital, he said.Pseudomonas Aeruginosa is a common bacteria found in moist ground and water, usually not contagious to a healthy human body.

But it can develop into an infection when an individual has a weak immune system.

The multi-drug resistant form is more alarming as it has developed resistance against a number of medicines.

The 13 people who contracted the bacteria were treated at the hospital on the northern island of Hokkaido from September 2006 to July last year, hospital official Kiichiro Igarashi said.

'We have not yet confirmed if they had become infected with the bacteria at the hospital,' he said.

The Japanese health ministry has ordered the hospital to investigate the cases and a possible link among the infected patients, he said. -- AFP