The head of the central government's liaison office shot down a proposal to let all voters nominate chief executive candidates, saying it's against the Basic Law. In a rare and high-profile gesture, the liaison office published a letter written by its director, Zhang Xiaoming, to the Civic Party, ruling out the idea of "civil nomination" - allowing contenders to run for the top post in Hong Kong if they obtain a certain proportion of voters' nominations. The methods for universal suffrage for the chief executive … should not deviate from the legal requirements. As a legal practitioner [you] should understand the legal principles should not be trespassed One academic said the letter, in which Zhang declined an invitation to attend a seminar on civil nomination, was a warm-up exercise in Beijing's propaganda war against the idea. Zhang's letter to Civic Party leader Alan Leong Kah-kit was dated August 30, but the liaison office only uploaded the letter yesterday. "The electoral method for the chief executive has to comply with the Basic Law," Zhang wrote. "Article 45 of the Basic Law states that nomination is by a broadly representative nominating committee … there is no other option. Civil nomination has neglected the requirements stated in the Basic Law." At a lunch with lawmakers in the Legislative Council last month, Zhang hinted that candidates for chief executive in 2017 should be screened. But Labour Party chairman Lee Cheuk-yan revealed that Zhang said a pan-democrat proposal - making 80,000 voters' nominations a threshold for candidates - did not comply with the Basic Law. Zhang told Leong in the letter: "The methods for universal suffrage for the chief executive … should not deviate from the legal requirements. As a legal practitioner [you] should understand the legal principles should not be trespassed." When asked last night whether he felt pressured by Zhang's statement, constitutional affairs minister Raymond Tam Chi-yuen replied: "No, the administration does not feel pressured in any way because we work according to the law … and we are a facilitator between sectors." Chinese University political scientist Ma Ngok said Zhang's gesture signalled a looming propaganda tussle over electoral reform. "By addressing the idea in such a high-profile manner, it is expected Beijing is going to stage a series of propaganda attacks on 'civil nomination' soon," he said. In Beijing, Vice-President Li Yuanchao urged senior civil service delegates to give their "steadfast support" to Chief Executive Leung Chun-ying. "The civil service is a crucial force in implementing the 'one country, two systems' and … the Basic Law," Li told Secretary for Civil Service Paul Tang Kwok-wai, who led 11 permanent secretaries and bureau directors.