Police baton charged opposition protesters for a second day
Security is tight in Sri Lanka's capital as the Supreme Court prepares to hear a challenge to the arrest of the losing presidential candidate.
Gen Sarath Fonseka was arrested on conspiracy charges on Monday, provoking clashes between his supporters and re-elected President Mahinda Rajapaksa.
The general has denied the allegations against him.
The US, EU and the UN Secretary General Ban Ki-moon have all urged the president to respect the legal process.
Gen Fonseka is appealing for calm, his wife announced on Thursday.
He made the plea through Anoma Fonseka after more violent clashes over his arrest.
The government has not detailed what charges Gen Fonseka will face, but Mr Rajapakse has alleged that he had "clearly been plotting a military coup".
Human rights groups have expressed disquiet at the general's arrest.
On Thursday the Hong Kong-based Asian Human Rights Commission warned that Gen Fonseka was being deprived of "due process" because his case was being handled in a military rather than a civilian court.
The opposition has said that the appointment of President Rajapaksa as the new minister for information is another worrying expansion of presidential power. The president already doubles up as defence minister and finance minister.
Last week the Supreme Court ruled that Mr Rajapaksa's new term would begin in November, giving him almost another year in power.