A SENIOR Taiwan official has cast grave doubts on Beijing's sincerity in putting promises on Hong Kong policy into action in the face of the present Sino-British political row. Chiao Jen-ho, a vice-chairman of the cabinet-level Mainland Affairs Council, said they had become more suspicious and worried about whether Beijing was sincere. ''For the sake of the well-being of the six million people of Hong Kong, we want to see the policy of 'one country, two systems' succeed. ''But following the recent political row and the scaring Chinese official remarks, we cannot but cast doubts on the sincerity of Beijing,'' he told a conference at Princeton University in New Jersey. Mr Chiao, who was recently appointed secretary-general of the Straits Exchange Foundation, urged Beijing to learn from Hong Kong. ''[It should try to] turn Hong Kong into a window through which it can break the ideological barriers and look at the world,'' he said. Mr Chiao said the policy of ''one country, two systems'' would not be acceptable to Taiwan - regardless of whether it succeeded in Hong Kong. However, he noted that the Taiwan Government was committed to maintaining and expanding its ties with Hong Kong. Chen Yizhi, a former close aide to disgraced Communist Party chief Zhao Ziyang, argued that the ''one country, two systems'' policy was only a transitional tactic. ''Its essence is first to stabilise Hong Kong and then swallow it,'' he said.