TOKYO (AFP) - Japan's defence ministry sent planes and helicopters to search for a military aircraft with four crew members aboard that went missing earlier on Monday (May 15).

The LR-2 reconnaissance plane disappeared from radar near Hakodate airport on the northern island of Hokkaido while flying to pick up a patient in Hakodate at the request of Hokkaido's governor, a ministry spokesman said.

"We have sent four helicopters and two airplanes to search for the missing plane," the spokesman said.

"So far we have not found any clues," he said, adding that the weather was poor, especially in the mountains.

The propeller aircraft was scheduled to take the patient from hospital in Hakodate to Sapporo, Hokkaido's capital city, for special medical treatment.