Japan's public broadcaster NHK and Kyodo News agency said Toyota, the world's No. 1 automaker, was considering recalling the vehicles but didn't name sources.
Toyota spokesman Hideaki Homma said the company was considering measures to deal with the problem of defective engines that can stall while the vehicle is moving. He would not confirm a recall was being considered.
The automaker has been working to patch up its reputation afterworldwide because of unintended acceleration and other defects.
Of the 270,000 vehicles with engine problems, some 180,000 were sold overseas and the rest in Japan. They include the popular Crown and seven models of luxury Lexus sedans.
Toyota said there have been no reports of accidents linked to the faulty engines. It did not say how it learned about the engine troubles.
The automaker's shares fell 1.1 percent to 3,045 yen in Tokyo on Thursday.
U.S. authorities recently slapped Toyota with a recordfor acting too slowly to recall vehicles with defects. Toyota dealers have repaired millions of vehicles, but the automaker still faces more than 200 lawsuits tied to accidents, the lower resale value of Toyota vehicles and the drop in the company's stock.
In the aftermath of the recalls, Congress is considering an upgrade to auto safety laws to toughen potential penalties against automakers, give the U.S. government more powers to demand a recall and push car companies to meet new safety standards.
Toyota said last week it willafter testing showed that fuel can spill during a rear-end crash.