Mr Bitar had issued an arrest warrant for Mr Fenianos after he failed to appear for questioning and rescheduled sessions for three other former ministers, who are also sitting legislators.
Former finance minister Ali Hassan Khalil was summoned on September 30 while former agriculture minister Ghazi Zeaiter and former interior minister Nouhad Al Machnouk were called for questioning on October 1.
All four, along with former prime minister Hassan Diab, had snubbed Mr Bitar’s previous summons, claiming, under the constitution, that he had no authority to question them.
Judge Bitar rescheduled Mr Diab’s hearing for October 4 after the former premier left for the US on holiday last week. Mr Diab said he was visiting his sons for four weeks.
The case has already led to the removal of one lead judge. Mr Bitar replaced Judge Fadi Sawan, who was removed by the Supreme Court after accusing Mr Diab of criminal negligence with Mr Hassan Khalil and Mr Zeaitar, both members of Parliament Speaker Nabih Berri’s parliamentary bloc. In a similar request to the Supreme Court, the two officials also asked for the removal of Mr Sawan.
Mr Fenianos has publicly claimed the investigation is being politicised.
The investigation into the deadly explosion that killed more than 214 people and destroyed large parts of the capital, has suffered several setbacks since the indictment of senior officials.
The families of victims and human rights organisations have accused politicians of stalling and blocking the inquiry after parliament failed to authorise the questioning of sitting MPs.
Parliament’s secretariat argued that indicted officials should be tried before a special body that brings together legislators and senior judges in line with the constitution.
Mr Bitar was also criticised by the Iran-backed militant group Hezbollah.
The top prosecutor's office asked Mr Bitar on Tuesday to respond in writing to allegations that Hezbollah threatened to remove him from the investigation.