At least 20 student leaders have been arrested in Myanmar in the biggest wave of arrests since the dissolution of the junta.

Friday's arrests come on the eve of a rally to commemorate a crackdown on a student movement, an activist said.

"Apart from those five arrested in Yangon... five student activists [were arrested] in Shwebo, six in Mandalay, four in Lashio," Thet Zaw, one of the leaders of a student uprising in 1988 that was brutally suppressed, told the AFP news agency.

Another veteran of that uprising - known as Generation 88 - said the five held in Yangon were "taken for no reason", adding that "the authorities said they wanted to talk with them".

Those arrersted by the Special Branch Police are from the groups 88 Generation Students Group, 2007 New Generation Students Union and the All Burma Federation of Student Unions.

Myanmar has witnessed a series of reforms since president Thein Sein took over from a military-ruled government last year, including the release of hundreds of political prisoners and elections which propelled dozens of  opposition party members to parliament.

Opposition leader Aung San Suu Kyi urged the government to release those still in custody on a high-profile trip to Europe which ended last week.

Legislators from her National League for Democracy party are currently in Naypyidaw, the capital city, attending a parliamentary session.

The Nobel Peace Prize winner is due to join the session on Monday.