YANGON, August 10, 2008 (AFP) - Five of 48 activists arrested as they marched to mark a 1988 pro-democracy uprising remain locked away in military-run Myanmar, an opposition member said Sunday.

Security officials seized the peaceful protesters as they marched Friday in western Rakhine State, said a local member of the National League for Democracy (NLD) party.

Friday marked the 20-year anniversary of the so-called 8.8.88 student-led uprising, when hundreds of thousands of people protested across the country and soldiers opened fire on the crowds, killing at least 3,000 demonstrators.

Thein Hlaing said the 48 youths rallying in Taunggok town included NLD members, workers and students. Some protesters wore white t-shirts reading, 'The time has come, let's unite.'

'Five NLD members, including a woman, are still in detention since they were arrested on Friday as 48 youths marched to mark the anniversary,' Thein Hlaing told AFP by phone from Rakhine.

'They didn't shout any slogans but just marched silently in the early morning,' he said.

They marched for 30 minutes before they were whisked away, he said, noting that authorities released 43 of the protesters late Friday.

The party has urged authorities to release the remaining five protesters.

'We haven't got any reply so far. We do not know where they were detained since their arrest. Their family members are worrying about them a lot,' Thein Hlaing said.

No remembrances were planned to mark the 1988 anniversary in Myanmar, and heavy police security was seen around Yangon to ward off any protests.

Myanmar has been ruled by the military since 1962. Detained democracy leader Aung San Suu Kyi led the NLD to an overwhelming election victory in 1990, but the junta never recognised the result and has kept her locked away.