The Zimbabwean government has dropped treason charges against Mr Welshman Ncube, secretary general of the main opposition party Movement for Democratic Change (MDC), his lawyer said.
He has been released from custody.
Mr Ncube's lawyer, Mr Innocent Chagonda, said he did not know why charges had been dropped against his client, who was arrested yesterday for allegedly urging his party's supporters to overthrow President Robert Mugabe's government.
He was the second high-ranking MDC official to be arrested after the party's president Mr Morgan Tsvangirai was arrested on Friday.
Mr Tsvangirai has been ordered held in custody for another month after appearing in court to face charges he incited protests aimed at toppling Mr Mugabe. He has been charged with treason, inciting public violence and contravening Zimbabwe's strict internal security laws. The treason charge carries a possible death penalty.
The charges came after the MDC and its leaders called on opposition supporters to stage five days of anti-government protests last week. Attempts to march in the streets were quickly crushed by state agents, but a week-long work stoppage was observed in major cities.
The MDC says the protests were aimed at showing peaceful but popular opposition to Mr Mugabe's governance, but the government said the call for mass action was tantamount to a coup.
Mr Tsvangirai, Mr Ncube and another senior party official are currently standing trial for allegedly plotting to depose Mr Mugabe ahead of 2002 presidential elections, which Mr Mugabe won. They deny those charges and say they were framed.
AFP