Belgian authorities on Saturday released 14 suspects detained over an alleged plot to free an al-Qaida prisoner because of lack of evidence, the Federal Prosecutor's office said. A court decided there was insufficient evidence to hold them for more than 24 hours, said Lieve Pellens, spokeswoman for the office. She said tightened police anti-terrorism measures triggered by the arrests Friday would remain in place over the holidays. "We think there is still a threat," Pellens said in a telephone interview. However she acknowledged that searchs of the suspects homes had found no explosives, weapons or other evidence to persuade the court to keep them in jail.