China’s main state broadcaster has attacked Baidu, the biggest online search company, in a move likely to fuel concern among foreign investors about the risks of operating in the Chinese internet industry.

CCTV, which is launching its own internet search engine, broadcast reports and published blog posts and commentary accusing Baidu of being a “monopolist” that abused its power and did not manage content responsibly.

Some observers interpreted the coverage as an attempt to discredit a competitor with consumers and advertisers ahead of CCTV’s annual auction of advertising slots.

“Could it really just be a coincidence that CCTV launches its own search engine and attacks Baidu at the same time?” said Xie Wen, a former head of Yahoo China.

Given the broadcaster’s role as a propaganda mouthpiece for the ruling Communist party, the reports also raise fears that a campaign against Baidu is the prelude to a wider clampdown on the vibrant internet sector.

The government has struggled to adjust its traditional propaganda approach as growing numbers of citizens go online for news and information, often from informal sources.

“Investors in Chinese internet stocks like Sina, Youku, Sohu, Tencent, Alibaba et al should be wondering if Baidu is the only target of this CCTV campaign, or if other firms are next,” said Bill Bishop, a Beijing-based investor, in a blog post.

On Wednesday, CCTV set up a page on its website under the headline “Trust is Gold”, claiming that it was participating in a government initiative. CCTV said it was “exposing false information, negative behaviour driven by unfair competition, and promoting the establishment of a healthy, fair online environment”.

But the page featured nothing but CCTV programming and online comment scathingly critical of Baidu.

“There are certainly some problems with the development of the internet in China,” said William Long, a software engineer and prominent internet commentator. “But letting an institution which doesn’t understand the internet and even has a hostile attitude towards it handle the issue is definitely the wrong approach.”

Both Baidu and CCTV declined to comment.