Image copyright Reuters Image caption Mitsubishi's eK Wagon was one of the models affected

Japanese carmaker Mitsubishi Motors has said domestic orders for its vehicles have halved since it revealed last week that it had been rigging fuel efficiency tests.

Company president Tetsuro Aikawa said the situation was "very serious" but said he had no plans to resign immediately.

He said he did not know if sales abroad had been affected yet.

Shares in the company have more than halved since the scandal broke.

Investors are worried that Mitsubishi Motors - Japan's sixth-largest carmaker - will face fines and compensation claims.

Last week, Mitsubishi admitted that it had falsified fuel economy data for four "minicar" models sold only in Japan.

The inaccurate mileage tests involved 157,000 of its eK wagon and eK Space, and 468,000 Dayz and Dayz Roox vehicles produced for Nissan. All were sold in Japan only.

Then on Tuesday, the company admitted to manipulating test data for the past 25 years, far longer than initially thought.

Mitsubishi fuel test furore More than 600,000 vehicles in Japan affected 157,000 Mitsubishi models

468,000 Nissan models

50% - the amount shares in Mitsubishi have fallen since the scandal erupted Reuters

Mitsubishi's board has formed a panel to investigate the case, and US regulators have also launched an investigation into whether car models complied with their fuel economy rules.

At a news conference on Wednesday, Mitsubishi Motors said that because of uncertainty about the potential damage to its brand it could not make forecasts for the financial year 2016-17.

But Mr Aikawa was able to announce better-than-expected results for the year ending in March 2016.

Mitsubishi Motors reported that its operating profit rose 1.8% to 138.4bn yen (£950m; $1.2bn) while revenue increased by 4% to 2.27 trillion yen.