BEIJING, June 6 (Reuters) - Beijing on Monday (Jun 6) warned Australia to "act prudently" or face "serious consequences" after Canberra accused a Chinese fighter jet of dangerously intercepting one of its spy planes over the South China Sea.

Australia has argued it is not unusual for it to undertake surveillance flights in the South China Sea - a region Beijing insists comes under its domain despite a 2016 Hague ruling that dismissed its claims.

China's stance has heightened tensions with the United States and its allies, which insist on freedom of navigation in the area.

Australian Defence Minister Richard Marles said on Sunday that a Chinese J-16 fighter intercepted a P-8 surveillance aircraft late last month, in a "dangerous" manoeuvre that put the safety of the Australian Defence Force crew at risk.

But Beijing hit back on Monday, saying it would "never allow any country to infringe upon China's sovereignty and security ... under the pretext of freedom of navigation".

"China once again urges Australia to earnestly respect China's national security interests and core interests, act and speak prudently to avoid a miscalculation occurring that results in serious consequences," foreign ministry spokesman Zhao Lijian told reporters.

The incident comes three months after Australia accused the Chinese military of shining a military-grade laser at one of Canberra's defence planes over waters north of Australia, which the previous government labelled an "act of intimidation".

Zhao said on Monday that China's military has always conducted operations in a "safe, standard and professional manner" in line with international law.

Last week, Canada also accused Chinese pilots of nearly causing a mid-air collision during recent encounters in international airspace as the Canadians took part in efforts to enforce United Nations sanctions on North Korea.

China's defence ministry retorted on Monday that its pilots took "reasonable, forceful, safe and professional measures" in response to "provocative behaviour" by the Canadian military.