An Indonesian budget airline jet suspected to have crashed into the sea just minutes after take-off from Jakarta had 62 passengers and crew on board, including 10 children, the transport minister said Saturday.

"The total number of passengers was 50 along with 12 crew," Budi Karya Sumadi told reporters, adding that the figure included seven children and three infants.

The Sriwijaya Air Boeing 737 lost contact with air traffic control about four minutes after take-off on its way to Borneo island.

An Indonesian budget airline jet is "suspected" to have crashed into the sea just minutes after the Boeing 737 lost contact with air traffic control on Saturday, the country's national search and rescue agency said.

"We deployed our team, boats and sea riders to the location suspected to be where it went down after losing contact," Bambang Suryo Aji, a senior official at the agency, told reporters.

The suspected crash site is near tourist islands just off the coast of Indonesia's sprawling capital Jakarta.

Sriwijaya Air's jet lost contact about four minutes after leaving Jakarta's Soekarno-Hatta international airport on its way to Borneo island.

It was unclear how many passengers and crew were aboard the Boeing 737-500, which has a capacity of about 130, when it left Jakarta's Soekarno-Hatta international airport Saturday afternoon.

The usual flight time is about 90 minutes over the Java Sea between Java island and Kalimantan, Indonesia's section of Borneo island.

Data from FlightRadar24 said the plane reached an altitude of nearly 11,000 feet (3,350 metres) before dropping to 250 feet. It then lost contact with air traffic control.

"Sriwijaya Air flight #SJ182 lost more than 10,000 feet of altitude in less than one minute, about 4 minutes after departure from Jakarta," the tracking agency said on its official Twitter account.

Broadcaster Kompas TV quoted local fishermen as saying they had found debris near islands off the coast of Jakarta, but it could not be immediately confirmed as having belonged to the missing jet.

Indonesia's transport ministry said it was probing the incident.

"A Sriwijaya (Air) plane from Jakarta to Pontianak (on Borneo island) with call sign SJY182 has lost contact," said ministry spokesman Adita Irawati.

"It last made contact at 2:40 pm (0740 GMT)."

The budget airline, which has about 19 Boeing jets that fly to destinations in Indonesia and Southeast Asia, said only it was investigating the loss of contact.

Indonesia's search and rescue agency and the National Transportation Safety Commission were also investigating, Irawati said.

In October 2018, 189 people were killed when a Lion Air Boeing 737 MAX jet slammed into the Java Sea about 12 minutes after take-off from Jakarta on a routine one-hour flight.

That crash -- and a subsequent fatal flight in Ethiopia -- saw Boeing hit with $2.5 billion in fines over claims it defrauded regulators overseeing the 737 MAX model, which was grounded worldwide following the two deadly crashes.

The Boeing jet thought to have crashed Saturday is not a MAX model and was 26 years old, according to authorities. 

“We are aware of media reports from Jakarta, and are closely monitoring the situation,” the US-based planemaker said in a statement.

“We are working to gather more information.”

Indonesia’s aviation sector has long suffered from a reputation for poor safety, and its airlines were once banned from entering US and European airspace.

In 2014, an AirAsia plane crashed with the loss of 162 lives. 

Domestic investigators’ final report on the AirAsia crash showed a chronically faulty component in a rudder control system, poor maintenance and the pilots’ inadequate response were major factors in what was supposed to be a routine flight from the Indonesian city of Surabaya to Singapore.

A year later, in 2015, more than 140 people, including people on the ground, were killed when a military plane crashed shortly after takeoff in Medan on Sumatra island.