SYDNEY (AFP) - China has sharply escalated cyber attacks on Australian companies this year in a "constant, significant effort" to steal intellectual property, according to a report published on Tuesday (Nov 20) that angered Beijing.

The investigation by Fairfax Media and commercial broadcaster Channel Nine comes just days after US Vice-President Mike Pence accused Beijing at the Apec summit of widespread "intellectual property theft".

The report said China's Ministry of State Security was responsible for "Operation Cloud Hopper", a wave of attacks it said were detected by Australia and its partners in the "Five Eyes" intelligence alliance - the US, Britain, Canada and New Zealand.

An unnamed senior Australian government official told Fairfax the activity was "a constant, significant effort to steal our intellectual property", while other officials expressed frustration that firms and universities were not tightening their security.

Cyber experts echoed the government sources, with US cyber-security company CrowdStrike saying it "noticed a significant increase in attacks in the first six months of this year".

"The activity is mainly from China and it's targeting all sectors. There's no doubt the gloves are off," CrowdStrike vice-president Mike Sentonas told Fairfax.

The alleged attacks took place despite an agreement between Canberra and Beijing last year "not to conduct or support cyber-enabled theft" of intellectual property and other commercial secrets.

The Chinese Foreign Ministry dismissed the report, saying it was "without foundation in fact".

The allegations are "unprofessional, irresponsible, and obviously have ulterior motives", ministry spokesman Geng Shuang told a regular press briefing.

"They are only playing up tensions and confrontation and do not help to maintain the common security of cyberspace," Geng said.

Australian government officials did not immediately respond to requests for comment.

Western governments have long accused hackers in China of plundering industrial, corporate and military secrets.

Last year, sensitive data about Australia's F-35 stealth fighter and P-8 surveillance aircraft programmes was stolen when a defence subcontractor was hacked with a tool widely used by Chinese cyber criminals.

In 2016, a security breach on the Bureau of Meteorology's system, which has connections to the defence department, was linked - by media - to China.