Copyright authorities have discovered the first case of virtual reality technology being used to spread pirated films, an official said on Friday.

Authorities said that a mobile phone app, Chengzi VR, illegally re-edited and re-digitalized films - without copyright authorization - using VR technology, and then posted the films on its platform. The films included Transformers and Ant-man.

Viewers could buy VR glasses through the app, download the pirated VR films and watch them on a mobile phone. The service started in July last year.

"The selling point was to watch VR films on mobile phones, even though the effect is rough," said Xiong Wei, deputy head of the copyright squad of integrated law enforcement in the cultural market in Beijing.

The glasses cost 200 to 300 yuan ($30 to $45), and most of the pirated VR films were clips involving a fight, gun battle or action scene, he said.

Xiong said the company that ran the platform, Beijing VR-TIME Technology Co Ltd, did not earn much profit from the copyright infringement.

"It was at the phase of attracting users. They received venture capital to run the platform," he said.

The company was fined 30,000 yuan and it deleted pirated films and clips from its app, Xiong said.

A national campaign to protect intellectual property rights, which began in July and will end in December, has targeted online movies, TV shows, news articles, mobile phone apps and e-commerce platforms, according to the National Copyright Administration of China.

Some 1,655 sites have been shut down and 274,800 links to offending sites deleted, according to the National Copyright Administration of China.

The annual campaign, called Internet Sword, began in 2005 and aims to tackle online copyright infringement of music, movies, literature, games, e-commerce and software. From 2005 to 2016, copyright supervisory departments handled 93,500 administrative cases, Zhou Huilin, deputy head of the National Copyright Administration of China, said on Thursday.

Some 5,560 cases involving online infringement were detected and 3,082 sites subsequently closed, he said.