HONGKONG'S controversial plans for constitutional reform were hit by a new salvo of criticism from mainland officials last night - the eve of crucial Executive Council talks on the territory's political blueprint. China yesterday criticised Britain for using what it described as the ''three-legged stool'' trick of allowing Hongkong a say on matters which were purely the prerogative of Beijing and London, and also accused the Governor, Mr Chris Patten, of escalating the confrontation by planning to table his package in the Legislative Council later this month. Beijing again made it clear it would not accept any compromise package which failed to converge with the Basic Law and passed through Legco after manipulation by the Hongkong administration. A host of warnings listed in the February issue of pro-Beijing magazine, Bauhinia, were quoted in a dispatch from the local branch of the New China News Agency (NCNA) last night. Speaking at last night's NCNA spring reception, local director Mr Zhou Nan said Beijing would not give way. The Chinese Government would not ''barter away principles'' on ''these cardinal issues between right and wrong''. And in what is seen as Chinese determination to veto the Legislative Council's right to decide the pace of Hongkong's democratisation, a senior Hongkong-based mainland official said in a veiled attack on the Foreign Secretary, Mr Douglas Hurd, that it waswrong for a senior British politician to say the time for the two sides to resolve Hongkong problems had gone. Mr Hurd, speaking after meeting members of the Co-operative Resources Centre in London last month, said the time for Beijing and London to resolve Hongkong affairs without taking the views of Hongkong people into account had gone. Without naming Mr Hurd, NCNA vice-director Mr Zhang Junsheng condemned the statement as ''carrying serious implications''. ''Such a saying is tantamount to saying we can do without the Joint Declaration . . . This is a very far-reaching suggestion,'' he said. China's latest attack came as fears grew of dissent in Exco on the wide-ranging package of reforms presented by Mr Patten during his October 7 policy address to Legco. It has been suggested that unrest within the Exco ranks is being marshalled by senior member Lady Dunn, who is understood to have the support of fellow councillors Mr Raymond Ch'ien Kuo-fung, Professor Felice Lieh-mak and Mr Tung Chee-hwa. Mr Ch'ien declined to comment last night, while Professor Lieh-mak has already said the reforms should not go ahead at the expense of Hongkong's economy. As if to give Exco a timely reminder of what might be at stake, shares continued to fall yesterday on the back of political fears, with the Hang Seng Index closing 53.62 points down on 5,697.78. The index has now lost 242 points, or 4.1 per cent, since January 27, when Beijing began its latest series of attacks against Mr Patten's reforms. According to government spokesman Mr Mike Hanson it is impossible to say how long Exco will discuss the Governor's package, although a statement will be released as soon as members reach a conclusion. The Bauhinia article blasted Mr Patten for planning to table his political blueprint in the legislature, and dubbed it the ''three violations'' reform package because it was in breach of the Joint Declaration, flouted convergence with the Basic Law and disregarded other understandings agreed by Beijing and London. The article accused Mr Patten of trying every means to increase the status of Legco so that the law-making body could rubber-stamp his package. Noting that Hongkong officials had recently defended the Governor's original model, the article said it showed Britain was determined to remain unco-operative and against convergence. However, China's position remained clear - it would neither accept the ''three violations'' model, nor would it accept any amended package passed by the legislature under manipulation by the Hongkong administration. The article said the joint accord clearly stipulated that important matters straddling 1997 would only be discussed and decided by the Chinese and British governments - there was no question that Legco had the power to make decisions on such matters. ''It [the legislature] has absolutely no right, through any motion, to overturn the Sino-British understandings and still less to falsify the Basic Law,'' it added. During his spring reception speech, Mr Zhou said: ''Come what may, we will resolutely safeguard our national sovereignty, territorial integrity and strictly abide by the Joint Declaration, the Basic Law and the various agreements already reached by the two sides so as to ensure a smooth transition and to maintain a lasting stability and prosperity in Hongkong. ''We will hope that the British Hongkong authorities will abandon their wrong position and return to the course of abiding by the Joint Declaration, the Sino-British agreements and of convergence with the Basic Law without any further delay.''