A RISING star in the dissident movement has fled China and made his way safely to the West through Hong Kong. Informed sources said yesterday that Wang Jiaqi, 34, who was detained by Beijing police in early March for helping organise a petition for labour rights, arrived in Hong Kong last Friday. The sources said the dissident, a graduate student in the Law Faculty at Beijing University, was granted asylum by a Western country and left Hong Kong on Thursday. Wang, a police officer for several years before his enrolment at Beijing University, escaped from a detention facility in his native Tangshan, a city in northern China where he was taken under heavy guard after his arrest. Chinese sources said the Ministries of Public Security and State Security had been ordered by the leadership to conduct a nationwide investigation of his daring escape and to take remedial measures to plug the loopholes. Sources in the dissident community said that although W ang joined the pro-democracy crusade after the June 4, 1989 massacre, he was deemed a rising star because of his leadership qualities. Early this year, Wang reportedly formed a non-governmental labour organisation of 100 activists to press for such rights as freedom to strike. Two other leaders of the unit, Beijing University law lecturer Yuan Hongbing and veteran trade unionist Zhou Guoqiang, were detained with Wang. Yuan and Zhou, who are being held incommunicado in Beijing, are expected to be given at least two to three years of ''re-education through labour'', according to Western diplomats. Aside from his association with the labour movement, Wang used his legal expertise to help a number of people sue the Chinese Government and enterprises for infringing their civil rights. While in Hong Kong, Wang, who is in good health except for an ear infection, reportedly told friends he had great expectations of the pro-democracy and labour movements. Wang, who is divorced, expressed confidence that the crusade could be strengthened in spite of the recent spate of arrests of its leaders. A Hong Kong government spokesman said yesterday that it was policy not to comment on ''individual cases.'' A spokesman for the Tangshan Public Security Bureau said he had no knowledge of the Wang case.