HEADTEACHERS invited to a New China News Agency briefing on ''educational issues'' were shocked to end up being subjected to an hour-long attack on Governor Mr Chris Patten's reform proposals. About 40 primary and secondary school headteachers were invited to tea with a vice-director of the Hongkong branch of the NCNA, Mr Zhang Junsheng, a week ago. But the headteachers, expecting to discuss post-1997 education policy in Hongkong, instead heard Mr Zhang lambast Mr Patten's plans. One headmaster said: ''Mr Zhang told us that Mr Patten was pulling little tricks; that he was insincere; that he was creating new obstacles for the success of the talks.'' Another headmaster said Mr Zhang ''was talking non-stop for a full one hour'', adding that he seemed ''keen to get his propaganda machine into full gear''. Headmasters said Mr Zhang spent the first half of the two-hour session criticising Mr Patten, fuelling suggestions the Chinese had found a new ''but sensitive'' target for their united front tactic. The unannounced meeting took place on April 23 - when the Sino-British talks on Mr Patten's political blueprint entered their second day. The principal of Valtorta College, Mr Chan Hok-man, who organised the meeting with an NCNA member, admitted the meeting was ''sensitive'' because it was a first for headmasters. He said Mr Zhang only started talking politics after a headmaster raised a question on the Sino-British row. The headteachers noted their representative in the Legislative Council, Mr Cheung Man-kwong, was not present in the meeting. Mr Cheung is the spokesman for the Hongkong Alliance in Support of the Patriotic Democratic Movement in China. While saying he understood the reasons behind the snub, Mr Cheung, also a United Democrat and president of the 50,000-strong Professional Teachers' Union, said: ''The fact that we hold different political views should not affect exchanges on a professional level.'' Among those present were Mr Hudson Soo Yee-yau, president of the Hongkong Subsidised Secondary Schools Council, and Mr Tsang Yok-sing, chairman of the pro-China Democratic Alliance for the Betterment of Hongkong and head of Pui Kiu Middle School. The principal education secretary for the Po Leung Kuk group of schools, Mr Mak Kwai-po, is believed to have been one of the few non-headmasters present. ''It is good [the Chinese] did not wait until 1997 before they made contact with teachers. A lot of the problems concerning education should be dealt with and discussed before the Chinese takeover,'' said Mr Soo, who is also head of Heep Woh College. Some headmasters were disappointed Mr Zhang did not make use of the meeting to voice concerns over Hongkong's education policy after 1997. Ms Lisa Yip Sau-wah, head of the Sha Tin Tsung Tsin Secondary School said: ''Headmasters are keen to know what the Chinese Government sees as its role in the education policy of the future special administrative region government.'' But Mr Tsang rebutted suggestions China was working on a united front. ''Everyone may think differently of the seminar,'' he said. ''I personally think a lot of time was spent on discussing education issues.''