Zambian opposition leader Michael Sata has been arrested for allegedly making a false declaration of his assets before September's general elections.
Michael Sata is a long-time opponent of the president
If he is found guilty of the charge, the Patriot Front party leader could face a minimum of two years in jail.
Mr Sata also faces other charges of sedition, espionage and defaming the poll winner, President Levy Mwanawasa.
"The government is very scared of me," Mr Sata said after his release on bail, AFP news agency reports.
The PF leader won most of the urban votes in the elections and believes he was cheated of victory.
His supporters staged violent protests after Mr Mwanawasa's victory.
The BBC's Musonda Chibamba in the capital, Lusaka, says police struggled to contain Mr Sata's chanting supporters who had gathered outside Lusaka's central police station while he was questioned inside by police for an hour.
After his release, Mr Sata told the BBC from his office that the police had not specified what he had lied about under oath on 11 August when he submitted his form to stand as a presidential candidate.
Under Zambian law, the candidates are required to state their assets and liabilities before they are allowed to contest.
"They want to intimidate me but I can't succumb to their intimidation," he said.
Mr Sata, whose nickname is King Cobra, campaigned for he what he called "Zambia for Zambians" and criticised the influence of economic partners like China.
He is due to appear in court on Wednesday 6 December.