Researchers at a Perth university say there’s a slim chance a low-frequency underwater sound that they’ve been analysing could be the missing Malaysian Airlines flight crashing into the Indian Ocean.

But Curtin University senior research fellow Alec Duncan also says the sound picked up by hydrophones off Rottnest Island at about 9.30am (WST) on March 8 could have come from a natural event such as a small earth tremor.

The Boeing 777 went missing in the early hours of that day on the way from Kuala Lumpur to Beijing with 239 people on board.

The Curtin researchers say the timing of the sound, which they believe originated from thousands of kilometres northwest of the current search area, made it of interest in the hunt for MH370.

The search co-ordinators, the Joint Agency Coordination Centre, said Curtin’s analysis of the signals was considered by the Australian Transport Safety Bureau (ATSB).

“However, Curtin University has concluded, and the ATSB agrees, that the current results are not compatible with the international search team’s analysis of the most likely area where MH370 entered the water,” JACC said.

“The ATSB will continue to discuss the analysis of this information with Curtin University for the purposes of informing the search.”

Separately, the ATSB is investigating a British yachtswoman’s claim she saw what she believed to be a burning aircraft in the sky above the Indian Ocean on March 8.

Katherine Tee, 41, told sailing site Cruisers Forum – a firm for which she also works – that she didn’t report the sighting to Australian authorities until this week because “there were two other planes passing over it – moving the other way” and she thought they would report it.

She said she also wasn’t sure of what she saw.