COLOMBO - Government troops killed at least 17 Tamil rebels and lost two soldiers in northern Sri Lanka, a military spokesman said on Tuesday.The fighting was spread out the Welioya, Mannar, Jaffna and Vavuniya areas, more than 250 kilometres north of the capital as troops conducted an offensive in rebel-held areas, the spokesman said. He said 10 rebels were killed in three separate clashes in Vavuniya while two soldiers were killed in Welioya and Mannar.