The Lebanese judge investigating the deadly 2020 Beirut port blast has resumed his work, a judicial source said, after a 13-month suspension due to political pressure.

"Judge Tarek Bitar has decided to resume his investigation," the official told AFP, adding that he ordered the release of five detained suspects, while charging eight others.

Among those charged by Bitar were Lebanese general security director Abbas Ibrahim and state security chief Tony Saliba.

The investigation into the cause of the blast had been stalled since December 2021 as politicians that Bitar had summoned for questioning filed complaints against him, forcing him to halt his probe.

"Bitar conducted a legal study that led him to decide to resume his investigations despite the complaints filed against him," the official said.

Lebanon's powerful Hezbollah group had also repeatedly demanded that Bitar step down from the investigation.

No state official has yet been held accountable over the blast.

Last week, Bitar met with two French judges about his investigation, a judicial source told AFP at the time.

The August 4, 2020 explosion at the Beirut port killed more than 200 people and destroyed swathes of the capital.

Authorities said tonnes of ammonium nitrate fertiliser haphazardly stocked in a port warehouse since 2014 had caught fire, causing one of history's largest non-nuclear explosions.