SWEDISH Prime Minister Mr Carl Bildt yesterday supported Hongkong's right to a say in its own affairs and said the defence of democracy and the rule of law were the best guarantees of future stability. But, like other recent Western visitors, he stopped short of specific endorsement of Governor Mr Chris Patten's electoral reform proposals, calling the details of the territory's 1995 electoral arrangements a matter for Britain and China. In a wide-ranging discussion of Sweden's foreign policy, Mr Bildt said his Government was determined to build economic and political relations with the Far East, particularly China, but would not sell arms to either the mainland or Taiwan. In a luncheon speech to the Foreign Correspondents' Club, he said that while China was opening up to the outside world and striving to be a world economic power, it would never be able to resist the pressures for change within its own borders. A society could never be half-free and half-slave, he said. The freeing of the Chinese economy would sooner or later make the transition to a free and open society respecting human rights and freedoms unavoidable. The future development of Hongkong was an essential part of the process. ''Although it is a matter that we hope will be resolved by Britain and China, we believe that a people that asks for a greater say in the running of its own affairs must never be denied this,'' he said. Asked if Sweden supported Mr Patten's constitutional reforms, the youthful conservative leader said it would be ''unfair and unwise'' to go into the details of how the elections were to be organised. ''It's not a question of other governments supporting the Governor,'' he said. ''I don't think he would like that. This is a process which is happening in Hongkong and between Britain and China.'' Noting that Sweden had a strong commercial and financial presence in Hongkong, with at least 130 Swedish firms established in the territory, Mr Bildt said the country was also actively developing economic and political links with China.