JAKARTA : A passenger aircraft with 102 people on board - including 11 children - went missing in Indonesia on Monday after sending distress signals, the transport minister said.

The Boeing 737 was flying between the cities of Surabaya, on the central island of Java, and Manado, on Sulawesi island, when contact was lost.

Transport Minister Hatta Radjasa said the Adam Air plane was believed to be near Mamuju in South Sulawesi province, 750 kilometres southwest of its intended destination in the northeast of the island, or about halfway.

"The plane with 96 people has lost contact and at this point its position is at Mamuju, based on the distress calls we've received," he told ElShinta radio, referring to the passengers. The plane was also carrying six crew.

"We have already instructed the search and rescue teams to send aid immediately to those injured in the incident," he said.

"We have no information on the condition of the plane or passengers. We have asked all aircraft crossing the area to relay any information they get," the minister said.

"We do not know the reason (for the plane going missing) so don't speculate. At this point we need to offer help to the 96 people as soon as possible."

The Surabaya airport duty manager said there were no technical problems with the plane when it took off.

The aircraft left at 12:59 pm (0559 GMT) and had fuel to last just four hours.

"We had lost contact and the plane had disappeared from radar at Makassar (in South Sulawesi) at 0707 GMT. It had lost contact at that position and disappeared from the screen," Air Transport Department director general Mohammad Iksan Tatang told reporters.

It was carrying 85 adults, 11 children, including four babies, and six crew.

"We had earlier coordinated with nearby airports in case the plane had to make an emergency landing but we have no concrete information of any such landing," he said.

"We are calling on all aircraft nearby to monitor any type of distress signal."

Tatang said he did not know what had happened but pointed out that the weather had been bad in recent days.

"We don't know for sure (the reason it is missing) but the weather in this region has been really bad, but before the plane took off they were fully aware of the weather conditions," Tatang said.

Adam Air air security director Captain Hartono said search and rescue work would start on Tuesday.

"A search and rescue team is already on its way to Mamuju. We expect rescue work to start tomorrow morning once they reach the location where the distress calls came from," Hartono said.

The area north of east Java is subject to violent storms, with high winds since last weekend. The sinking of a ferry carrying 600 people off Java on Friday night has been blamed on bad weather. Radjasa has been dealing with that disaster.

Privately owned Adam Air began operations in 2003 and serves mostly domestic routes, with Singapore and Malaysia's Penang its only international destinations.

The company is a leading low-cost carrier in the competitive Indonesian market, marketing itself as a "boutique airline" between traditional budget firms and regular airlines.

Company president director Adam Suherman said in November Adam Air planned to beef up its fleet by an additional 10 planes next year to handle a projected rise in passenger numbers.

According to Adam Air's website, the carrier had 19 Boeing 737 jets in its fleet as of January 2006.

The airline expects to handle 11 million passengers in 2007, up from an estimated seven million in 2006.

Suherman had said the carrier would concentrate on its domestic market, which is still largely untapped.

"Indonesia has a very huge market potential with a population of over 250 million and less than 10 percent presently travel by air," he said.

He has also announced plans to list in Singapore by the middle of 2008.

Aircraft accidents are not rare in Indonesia, a vast archipelago nation stretching over 5,000 kilometres.

Public and private Indonesian airlines have been repeatedly criticised over their poor safety records, repeated delays and bad management. - AFP/dt/de