Myanmar police beat students with batons and detained some of them as they broke up a group of about 200 protesters who had been locked in a standoff with security forces for more than a week, a Reuters witness said.
The students were protesting an education bill they say stifles academic independence, and a group of them set out on foot from the central city of Mandalay more than a month ago in a symbolic protest.
They made it as far as Letpadan, a town about 140 km (90 miles) north of Yangon, where police blockaded them behind vehicles and barriers made of wood and barbed wire.
Although the police initially said they would allow the students to continue their march on Tuesday, the agreement fell apart. Riot police moved into the protest site and used batons to beat students, monks who had join the protest and journalists, said the witness.
Police chased the students and monks into a Buddhist monastery where they had taken refuge, said the Reuters witness.
The witness saw police using the batons to smash the windows of a car belonging to a student and an ambulance where some protesters had taken shelter. Five students were arrested in Letpadan on Friday, and the United States, which in recent years has backed political reforms in Myanmar, expressed concern at the developments.
The students were later freed. Yangon is the site of numerous student-led demonstrations, including those in 1988 that sparked a pro-democracy movement that spread throughout the military-ruled country, and the government had barred them from entering the city.
Military leaders brutally suppressed the 1988 protests in Myanmar and were subsequently overthrown by another group of generals who continued to restrict democratic freedoms and imprisoned thousands of activists, artists and writers. A semi-civilian reformist government took power in 2011 after 49 years of military rule.
Its response to the current student protests has been more muted. However, on Thursday, police and plain-clothes vigilantes detained eight people who had gathered in downtown Yangon to show solidarity with the Letpadan protesters.
Some were beaten with batons, witnesses said. The eight were later freed.