SEPANG, Malaysia — After four days of reticence and evasive answers, the Malaysian military acknowledged on Wednesday that it had recorded, but initially ignored, radar signals that could have prompted a mission to intercept and track a missing jetliner — data that vastly expands the area where the plane might have traveled.

Radar signals from the location where the missing aircraft, Malaysia Airlines Flight 370, was last contacted by ground controllers suggested that the plane may have turned away from its northeastward course toward Beijing, officials said. Military radar then detected an unidentified aircraft at several points, apparently headed west across the Malaysian peninsula and out into the Indian Ocean, the head of the country’s air force told reporters. The last detected location was hundreds of miles to the west of where search and rescue efforts were initially focused.

The military took no immediate action on Saturday to investigate the unidentified blips, whose path appeared to take the aircraft near the heavily populated island of Penang, and only later realized the significance of the radar readings. The search area was then expanded to take in waters west of the peninsula as well as east — encompassing almost 27,000 square nautical miles, an area bigger than South Carolina — but officials did not give a full explanation for the move.