The prosecution ordered on Wednesday to release leader of the Yemeni Socialist Party, one of the opposition coalition parties, Muhammad Ghalib who was arrested days ago for allegedly having links with and financing separatists and saboteurs in the south.
He was released due to lack of evidence, prosecutors said.
Official spokesman for the Joint Meeting Parties Muhammad Al-Qubati said they had heard about the release decision but Ghalib was still in custody.
Also, sources close to Ghalib's family said that the family was informed he was ordered released, but the Criminal Investigative Department asked for bail to release him.
Ghalib was arrested on Sunday morning at his house in Sana'a after a separatist leader said in a statement that the Joint Meeting Parties JMP provided YR 10 million through Ghalib in support of southern separatists and saboteurs.
He was also accused of involvement in the twin attacks against a sports club in Aden ahead of the 20th Gulf soccer championship with the aim to thwart hosting the event.
First, the prosecution decided to hold him for two days to complete his investigation, but later it extended the period to a week.
After the statement, the Interior Ministry threatened opposition leaders were likely to be investigated on charges of conspiracy and involvement in supporting sabotage.
In case the statement proves true, such investigations will be inevitable, it said on its website.