Hundreds of police have formed a human chain around student protesters staging a sit-in on a road after being blocked from marching to Burma's biggest city.
The demonstrators - who have been rallying for more than a month and gaining public sympathy - want the government to scrap a newly passed education law that they say curbs academic freedom.
They were outnumbered by police in the town of Letpadan, about 90 miles from Rangoon, but neither side appears willing to back down. Security forces formed rows around the students four layers deep.
Burma started moving towards democracy in 2011 following a half-century of military rule, but critics say the reforms that marked president Thein Sein's early days in office have either stalled or been rolled back.
The education law, passed by parliament in September, puts all decisions about policy and curriculum in the hands of a body made up largely of government ministers.
It bans students from forming unions and ignores calls for local languages to be used in instruction in ethnic states.
Students say the law undermines the autonomy of universities, which are still struggling to recover after clampdowns on academic independence and freedom during years of dictatorship.
Police have repeatedly warned they would "take action to restore law and order" if the protesters tried to bring their rally to Rangoon, 90 miles south of Letpadan. Negotiations have been inconclusive.
The threat of an expanded protest is sensitive in Burma, in part because students were at the forefront of pro-democracy protests in 1988 that were crushed by a bloody military crackdown.