Nearly five tonnes of liquid waste containing an estimated 120,000 lethal doses of sodium cyanide has leaked from a Japanese factory in the northern Japanese city of Hanamaki in Iwate Prefecture.

The deadly liquid seeped out following an accident. A snowplough had mistakenly hit a tank containing the liquid while clearing snow in the region, said officials.

The Tokyo-based firm, Kurosaka Planting, has been involved in the removal of nickel plating from surfaces and said the leak has so far not created any health issues for nearby residents.

"Fortunately, snow absorbed most of the liquid and we have been able to collect the contaminated snow. The leak has not reached a nearby river and we have not received any reports of impact on people," said a spokesperson for the company.

Japan had witnessed heavy snowfall in the previous week and piles of snow had blanketed the site. A valve in the tank in which the liquid was stored was damaged when workers were cleaning the area.

Officials have initiated a probe into the incident. Compounds of cyanide are highly toxic to humans, and are used in murders and suicides.

Japan has recorded nearly 70 deaths this winter following bad weather.