Troubled by almost daily suicides using toxic hydrogen sulphide gas, which in some cases has sickened other people or forced them to evacuate their homes for hours, Japanese firefighters have developed a simple tool to neutralise the fumes.

Hydrogen sulphide gas can be produced from household detergents and there have been scores of cases of the fumes being used by people taking their own lives this year, often using instructions posted on the Internet.

The new gadget uses a fan to draw the gas through a plastic box containing activated carbon, a porous form of charcoal, said the Osaka city fire department, which developed the gadget.

An experiment at a suicide site this week removed all the poison gas in 30 minutes, a fire department spokesman said.

Previously those living near the scene of a gas suicide were forced to evacuate for long periods to allow fumes to disperse.

The apparatus, which can be made mostly from everyday items, costs less than 10,000 yen (48 pounds), the fire department said.

"We are offering this information because we think it could be of use all over the country," the spokesman said.

Japan has the second-highest suicide rate among major industrialised countries after Russia. The annual number of suicides has been above 30,000 for a decade, government figures show.

The government has pledged to cut the number of suicides by 2016, including by raising society's awareness of depression.