A council in Japan has adopted a ruthlessly efficient method of dealing with stray dogs and cats: mobile extermination vehicles with pet-sized gas chambers.

The so-called death trucks were introduced after residents of Tokushima prefecture, in south-east Japan, said they did not want animals destroyed in their neighbourhoods.

The council's solution has been to kill dogs and cats while en route to a regional crematorium.

The animals are shut inside airtight metal boxes termed ''sedation equipment'', which measure 1.2 metres high and wide and 1.5 metres deep, officials told Japan's Asahi Shimbun newspaper.

Once the eight-tonne truck is mobile, the driver pushes a button that releases carbon dioxide into the boxes, the paper reported.