Nissan Motor had delivered only 60 units of its Leaf electric vehicle in Japan as of Friday, Kyodo News reported, despite already taking 6,000 orders due by the end of March.
Nissan denied any delay in the delivery of the pre-ordered cars and company spokesman Mitsuru Yonekawa told AFP on Tuesday that the automaker was taking a cautious approach to ensure quality control.
"We have to make sure that everything is 100 per cent safe and sure," Yonekawa said.
"This is the first time we have mass-produced an electric vehicle so we need to be very careful. We are not delayed or behind schedule," he said, adding that Nissan would ramp up production to meet its 6,000 units target by 31 March.
Another factor behind the slow pace was the time taken for consumers to complete the procedure for receiving a government subsidy for electric vehicles, Yonekawa said.
Government incentives to encourage Japanese buyers to purchase electric vehicles would mean a 780 thousand yen ($9,400) reduction off the price of a 3.76 million yen ($45,000) Leaf, available until the end of March.
Nissan's launch of the Leaf in Japan on 20 December and days later in the United States was seen as a bet on drivers' readiness to embrace the first globally mass-produced electric car.
The Leaf -- short for Leading Environmentally-friendly Affordable Family car -- enjoyed a crescendo of industry buzz in the build-up to its launch and was the first electric vehicle to win European Car of the Year.
Nissan and its French partner Renault have staked their future on electric vehicles and plan to launch several models by 2014 to meet rapidly rising demand for more environmentally-friendly methods of transport.
They have invested EU4 billion ($5.2 billion) in the programme.
Renault has suspended three top managers for allegedly leaking secrets about its electric car programme to China, despite angry denials from Beijing that it played any role in the incident.