National Basketball Association star Yao Ming has signed a three-year advertising contract with telecom company China Unicom, his first with a domestic firm. Unicom is China's second biggest mobile operator, with 12.1 per cent of the national telecommunications market. Its biggest rival, China Mobile, has 37.4 per cent of the market, according to figures published by the Ministry of Information Industry last week. A Unicom official said it had selected Yao as he was one of China's most popular sports stars whose future success would mirror that of the company. 'His self-confidence, energy and technical superiority are exactly those things we want in the new Unicom brand,' he said. Yao will be advertising the company's new Xin Shikong ('new space and time') CDMA mobile, with the first adverts to be screened on Friday, the eve of the Lunar New Year. The Unicom official said the advertisement was the most costly in the company's history. Intense negotiations with Yao were conducted in secrecy, with filming done in the United States. The finished product reportedly arrived back in China at the end of last week. The official declined to give payment details, saying they were a commercial secret, but described the amount as being at an 'international level'. Speaking from Shanghai, Yao's lawyer, Wang Xiaopeng, also declined to reveal the amount. 'Many Chinese companies want to use Yao in their advertising, and Unicom is the first domestic firm to have signed a contract,' he said. 'It is not only a question of money but what kind of product is suitable for him.' Other contracts were currently under negotiation, he said. Yao has signed endorsement contracts with several US companies, including Visa, Apple Computers and Sorrent, a California-based gaming firm that aims to create an interactive game named after him. Yao Ming Basketball is expected to be available on the mainland, Hong Kong and Taiwan in the first half of this year. US viewers watching the Superbowl on Sunday saw an advertisement featuring Yao trying to make a purchase without identification and attempting to convince the sales clerk he really was Yao Ming.