Police in Burma rounded up at least 16 student leaders ahead of the 50th anniversary of a brutal army crackdown, activists and family members said yesterday, raising doubts about the government's reformist credentials.

The activists were picked up in four different cities late on Friday and taken to undisclosed locations on the eve of the military's suppression of student protests in 1962. Among those arrested was 23-year-old Phyo Phyo Aung, the secretary of All Burma Students Union and a former political prisoner freed last year in an amnesty.