Authorities in Myanmar have released 20 student leaders detained during the fiftieth anniversary of an army crackdown, a political activist has said.

Saturday's release comes a day after several people were picked up in Yangon, Mandalay, Lashio and Shwebo on Friday night. They were then sent off to undisclosed locations.

Phyo Phyo Aung, a former political prisoner who was among those held, said they were freed late on Saturday.

Phyo Aung, a member of the All Burma Students Union, said she and three other members of the group were questioned at a building in Yangon that was once a Home Ministry office, because their organisation had been deemed illegal.

"Police officials told us that they just wanted to question us in connection with our plans to commemorate the anniversary," she told the Reuters news agency, referring to the army's suppression of protests in 1962 when dozens of students were killed and a university building blown up.

'Act of oppression'

The arrests could prove detrimental to the improvements the government has seen in its image at home and abroad since enacting a series of reforms last year.

"This act of oppression has given us the impression that the old ways of practice are still in effect, despite all the
positivity for change that we have been hearing," Cambodian politician Son Chhay, vice president of the ASEAN Inter-Parliamentary Myanmar Caucus, said in a statement.

"If they are even going to arrest people before any crime has taken place, this shows that they continue to use fear and
intimidation to repress", said the group of southeast Asian politicians providing support to Myanmar's democratic transition.

Friday's arrests were the largest crackdown on dissent since the end of military rule last year.

The military seized power in 1962 and ruled the country under various guises until March last year.

Opposition leader Aung San Suu Kyi urged the government to release all political prisoners during a high-profile trip to Europe which ended last week.

The US and European Union have suspended some sanctions in recent months in response to reforms by the new quasi-civilian government, which include moves to liberalise the economy, the release of more than 600 political prisoners and the introduction of laws allowing demonstrations.

However, despite government claims that the reforms are "irreversible", the arrest and detention of dissidents still goes on, albeit not as often, which rights groups say proves the retired generals still in power are not fully committed to
promises they have made.

Source: Agencies