The human rights organisation Amnesty International has condemned the arrests in Malaysia of several opposition leaders on charges of sedition and leaking state secrets, describing the move as "selective prosecution".

In a statement issued on Saturday, Amnesty said "charging political leaders and journalists with sedition threatens to strike at the heart of free speech in a democratic society".

The state crackdown started on Wednesday with authorities arresting five of the government's most prominent critics, three from the party of the jailed opposition leader Anwar Ibrahim and two publishers.

"When such prosecutions appear to fall solely on opposition figures, public confidence in the rule of law risks being seriously undermined," the organisation warned.

Three of those arrested pleaded not guilty on Friday to charges levelled against them in the Malaysian courts.

Lawyer Karpal Singh, who is acting for the jailed former Deputy Prime Minister Anwar Ibrahim, and opposition leader Marina Yusoff were accused of making seditious remarks.

Another senior figure in Mr Anwar's National Justice party, Mohamad Ezam Noor, was charged with violating the official secrets act.

On Thursday Zulkifli Sulong, editor of the Harakah newspaper, and publisher Chia Lim Thye appeared in court on charges on sedition.

'Selective but fair'

A senior government official has defended the arrests, saying they were made in the interests of national security.

"Their actions could endanger the nation, so these people are brought to court in accordance with the law," Foreign Minister Syed Hamid Albar told reporters on Friday.

He said the trials would be conducted in an open court and he denied they were designed to silence critics of Prime Minister Mahathir Mohamad's administration.

"Where in the world does prosecution not exercise discretion?" he asked.

"Therefore if you exercise discretion it is selective, but it must be just and fair" he said.

"It is not up to international bodies to determine how we should administer our laws," he added.

Crackdown denial

On the day the arrests were made, Mr Mahathir left for a two-week holiday overseas.

Malaysia's sessions court charged Karpal Singh, a long-time critic of the prime minister, with sedition after he alleged at Mr Anwar's sodomy trial that "people in high places" had tried to poison his client.

A court also charged Ms Yusoff, a leader of the National Justice Party, with sedition.

Prosecutors for the court, in northern Penang state, accused her of trying to incite racial unrest with comments she made during a political speech last year.

All three opposition figures were freed on bail.

Deputy Prime Minister Abdullah Ahmad has denied the arrests mark the start of a widespread crackdown on the opposition.

A senior police officer told the Reuters news agency on Saturday that there would be no more arrests.

Mass campaign

The opposition has called for a mass campaign to persuade the government to withdraw its charges against the five opposition figures.

Karpal Singh said it was the first time in any Commonwealth nation that a lawyer was prosecuted for something said during a court hearing.

He said the case would test the independence of the judiciary and the status of lawyers in Malaysia.

The Malaysian Bar Council is meeting on Saturday to decide whether to hold an Extraordinary General Meeting to discuss the sedition charge against Mr Singh.

More than 50 lawyers signed a petition calling for the meeting, and warned the case could set a dangerous precedent.

Malaysia has been in political turmoil since Anwar was fired in September 1998.

His subsequent arrest and conviction on corruption charges provoked massive anti-government demonstrations.

He is now serving a six-year prison term and standing trial for sodomy.

He has denied all the charges against him and says he is the victim of a political conspiracy to destroy both him and the growing movement against Prime Minister Mahathir.