JAKARTA (Reuters):

Indonesia focused rescue efforts on Sulawesi island late yesterday after an Adam Air Boeing 737-400 plane went missing with 96 passengers and six crew on board.

Contact with the plane was lost yesterday when it was at an altitude of 35,000 feet, about an hour before it was due to land in Manado in North Sulawesi, said Tatang Ikhsan, director general at the Transport Ministry.

Ikhsan said on Elshinta radio the flight had originated in Jakarta with a stop in Surabaya on Java island. It had left Surabaya at 1:00 p.m. (0600 GMT) and had been scheduled to land just over two hours later in Manado.

At a news conference late yesterday, he said a Singapore satellite had picked up a distress signal from a plane 83 nautical miles north-west of Makassar, the capital of South Sulawesi province, 1,400km (870 miles) east of Jakarta.

"We call on other flights which crossed this route to provide information on any distress signal," he said.

Transport Minister Hatta Rajasa said the plane had been sighted above the Mamuju forest on Sulawesi.

"(It was) preliminary information from a plane flying above it. It will be the first clue for SAR (Search and Rescue) to move to the area," he told Elshinta radio, adding that rescuers had already been ordered to go.

"Let's hope it made an emergency landing," he said.

First Marshall Eddy Suyanto, commander of Hasanuddin air base in Makassar, told Metro television: "We have contacted related agencies and several groups have travelled by road to locations where we think the plane might have gone down but so far there has not been any information."

The Transport Ministry's Ikhsan said the plane was airworthy and last serviced in December 2005. It has 45,371 flying hours.

"The weather conditions all over our country are not very good. We have notified all airlines ... All flights should have received complete information," he said.

Much of Indonesia was cloudy with rainfall yesterday.

An Adam Air Boeing 737-300 plane was forced to make an emergency landing in February at a small airport in East Nusa Tenggara province after a navigational failure caused the pilot to lose contact with the destination airport in Makassar.