Two former employees of Australian gas producer Santos are among four people missing, feared dead, in the Philippines following a light plane crash not far from the crater of an active volcano.
The country's official information agency said wreckage of what appeared to be the twin-engine Cessna 340A had been spotted by aerial search crews on Mount Mayon in Albay province.
The plane took off from Bicol International Airport on Saturday morning, and had been due to land in Manila just over an hour later, but lost contact with the control tower.
Among the four on board the six-seater were Adelaide men Simon Chipperfield and Karthi Santhanam — technical consultants of geothermal energy company Energy Development Corporation (EDC), and both former employees of Santos.
LinkedIn profiles for both men list them as residing in Adelaide.
The plane's pilot was Rufino James Crisostomo Jr, and crew member Joel Martin was also on board, the Philippine Information Agency (PIA) has said.
Australia's Department of Foreign Affairs and Trade (DFAT) said it was aware of reports that aviation authorities had lost contact with a light aircraft on Saturday.
"The Australian Embassy is in contact with local authorities and DFAT officials are providing consular assistance to the families of two Australians reported to be missing," it said.
"Our thoughts are with their families, friends and loved ones at this difficult time."
Search and rescue efforts are currently underway and wreckage of the plane has been located by first responders along a gully, at an altitude of about 6,000 feet, with debris spotted in a tree.
Complicating the operation is the fact that the crash site is "within the six-kilometre danger zone of Mayon volcano, which is currently under alert level 2 due to increasing unrest", the PIA said on Facebook.
Aerial photos show what appears to be a tail fin about 350 metres from the crater.
More than 250 people, 11 drones and four dogs are taking part in the operation.
It has also been reported that a resident sighted the missing aircraft, before a "loud banging sound was heard".
In a statement, Santos said both men worked at the company "for many years" and "have a number of friends and former colleagues throughout the Adelaide and Brisbane offices".
"Representatives from the Employee Assistance Program (EAP) have been arranged to be on site in both our Adelaide and Brisbane offices during this difficult time," a spokeswoman said.
"Our thoughts are with Simon and Karthi's families and loved ones."
In a statement, EDC said it has yet to verify if it is indeed their company plane RP-C2080 that was reported missing shortly after taking off from the Bicol International Airport.
"Our efforts remain focused on the safe rescue of the four passengers and we will not stop until they are found," said Allan Barcena, assistant vice-president and head of corporate relations and communications at EDC.
The company said it was also in constant communication with their families since they were first informed on Sunday.
