Michio Kanda, 58, set off on the voyage from eastern Japan on Thursday, aiming to reach Portland, Oregon in 60 hours, a support group member said.

But contact with Mr Kanda, a balloonist with 30 years experience, was lost early on Friday morning, shortly after he crossed the international dateline.

'We'd received calls from him every two hours over a satellite phone since he departed,' the group member said.

'In the last call, he said it was raining a little, but that things were going well.'

The group has contacted over 20 authorities in Japan, the United States and Canada, but there had been no word of progress in their searches, the support group member said.

The US Coast Guard said on its Web site that a rescue plane was searching around Kanda's last known position, while a patrol boat was also being sent to the area.

Mr Kanda was aiming to become the first Japanese balloonist to cross the Pacific Ocean alone. His balloon, measuring 50 metres high and 40 metres wide, is designed to carry around 100 people.

Mr Kanda tried to make the same voyage in 2004 but failed after bad weather and a fuel shortage forced him to ditch in the sea. -- REUTERS