(Adds CEO comment, details on results, background)

Feb 22 (Reuters) - China's Baidu Inc beat revenue estimates for the fourth quarter on Wednesday, bolstered by strength in its advertising, cloud and artificial intelligence businesses.

The search engine giant, which generates most of its revenue from online ads, is seeing advertisers return after China lifted its zero-COVID policies last year in a boost to the country's economic prospects.

The company also announced a new share repurchase program of up to $5 billion.

Quarterly revenue came in at 33.08 billion yuan ($4.80 billion), inching past analysts' estimates of 32.01 billion yuan, according to Refinitiv data.

Revenue from Baidu Core, which includes search-based ad sales, cloud offerings and its autonomous driving initiatives, fell 1% to 25.7 billion yuan.

Baidu's research and development expenses were 21.4 billion yuan, accounting for 22.4% of revenue, as it plans to integrate its ChatGPT-like Ernie Bot into cloud, smart cars and household appliances, among other mainstream businesses.

The AI-driven chatbot, seen by many as China's most promising answer to the platform developed by OpenAI and backed by Microsoft Corp, will complete internal testing in March.

"The Chinese AI market is on the verge of experiencing an explosive growth in demand, releasing unprecedented and exponential commercial value. Baidu stands as the best example of the long-term growth of China's AI market and is advancing at the forefront of this new wave," Baidu CEO Robin Li said.

Li added that the developers of Ernie Bot were sparing no effort to ensure the chatbot was made available as early as possible. ($1 = 6.8963 Chinese yuan renminbi) (Reporting by Yuvraj Malik in Bengaluru; Editing by Devika Syamnath and Shounak Dasgupta)