By Lewis Jackson

SYDNEY (Reuters) - A Chinese fighter jet endangered those aboard an Australian military helicopter during an "unsafe" and "unacceptable" confrontation over the Yellow Sea last week, Australia said on Monday.

The incident occurred on Saturday, when a Chinese air force J-10 jet dropped flares above and several hundred meters ahead of an Australian MH60R Seahawk helicopter which was on a routine flight in the Yellow Sea as part of an operation to enforce sanctions against North Korea.

The helicopter, flying from destroyer HMAS Hobart, took evasive action and dodged the flares, but the possible impact of being hit would have been "significant," Defence Minister Richard Marles said in a statement.

"This is a very serious incident, it was unsafe and it is completely unacceptable," he said.

"We have formally expressed our concerns about this incident, and formally expressed that this was both unsafe and unprofessional."

The incident put the aircraft and those on board at risk, although no one was hurt, the Department of Defence said in a separate statement.

Australia said it has been participating in missions to enforce sanctions against North Korea in the region since 2018. The HMAS Hobart continues to operate in the area.

China's Ministry of Defence did not immediately respond to a request for comment.

(Reporting by Lewis Jackson; Editing by Bernadette Baum)