Mitsubishi Motors has admitted falsifying fuel economy test data which could affect more than 600,000 vehicles, including some produced for Nissan.

It is believed the four models affected are available only in Asia: the Mitsubishi eK Wagon and eK Space, and the Nissan Dayz and Dayz Rooxs.

Mitsubishi said it has stopped making and selling the vehicles and had set up an independent panel to investigate.

Mitsubishi Motors president Tetsuro Aikaw said: "We have discovered that improper tests that were meant to show fuel consumption better than they actual were, were being used. It was also found that the fuel economy testing methods used were not in line with Japan regulations.

"We offer our profound apologies to our customers and all stakeholders for this."

The inaccurate tests involved 157,000 of its own brand light passenger cars and 468,000 vehicles produced for Nissan.

The problem was uncovered after Nissan pointed out inconsistencies in emissions data. Mitsubishi then conducted an internal investigation and found that figures had been falsified.

Lance Bradley, managing director of Mitsubishi Motors in the UK, says: “Mitsubishi Motors Corporation has acted quickly and decisively. We understand that such issues are of great concern to consumers. I would like to reassure everyone that there is no evidence to suggest that UK or European models are affected’.