Japanese carmaker Mitsubishi Motors has admitted manipulating emissions tests on some of its own brand and Nissan cars in the wake of the scandal at German rival, Volkswagen.

The company spoke out after initial reports vehicles had failed testing sparked the biggest one-day fall in its share price for 12 years - losing 15%, or $1.2bn, of its market value by the close of trading.

Mitsubishi confirmed there was evidence to suggest employees falsified emissions test data for several models, involving 157,000 of its own brand light passenger cars and 468,000 vehicles produced for Nissan.

It is understood the bulk of the vehicles affected were sold in the domestic Japanese market and further details were being given at a news conference in Tokyo.

Mitsubishi president Tetsuro Aikawa has told reporters the wrongdoing came to light because Nissan alerted it to inconsistencies in emissions data. He said Mitsubishi's internal probe uncovered the manipulation by staff.

He said Mitsubishi's internal probe uncovered the emission cheating.