Image source, ReutersImage caption, No one has been held accountable for the port explosion, which killed more than 200 people

Lebanon's highest court has dismissed requests to replace the judge leading the investigation into last year's devastating explosion at Beirut's port.

Tarek Bitar had to pause his probe last week after three former government ministers wanted for questioning filed complaints that accused him of bias.

Victims' families and human rights groups condemned the suspension.

No one has yet been held accountable for the August 2020 blast, which killed 219 people and injured 7,000 others.

A fire triggered the detonation of 2,750 tonnes of ammonium nitrate, a combustible chemical widely used as agricultural fertiliser, that had been stored unsafely in a port warehouse for almost six years.

Senior officials were aware of the material's existence and the danger it posed but failed to secure, remove or destroy it.

Media caption, One year on from the Beirut blast

Victims' relatives and activists say the investigation into the explosion is being hampered by the Lebanese political leadership's efforts to shield politicians and officials from scrutiny.

The Court of Cassation, which is equivalent to the Supreme Court, removed the first lead judge earlier this year after he charged senior officials with negligence – the prime minster at the time of the explosion, Hassan Diab, former finance minister Ali Hassan Khalil, and former public works ministers Youssef Finyanus and Ghazi Zaiter.

The four men denied any wrongdoing and refused to be questioned as suspects, accusing the judge of overstepping his powers.

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Judge Bitar was suspended after a fourth politician wanted for questioning on suspicion of negligence, former interior minister Nohad Machnouk, requested his removal. Mr Machnouk also denies wrongdoing.

Mr Khalil and Mr Zaiter filed similar complaints against the judge days later.

On Monday, the Court of Cassation rejected all three lawsuits, explaining that it did not "have the prerogatives to rule over this matter", a court official told AFP news agency.

The official said Judge Bitar could resume his investigation immediately and that he was expected to seek to question Mr Machnouk, Mr Khalil and Mr Zaiter before parliament goes back into session on 19 October, after which they will benefit from immunity from prosecution as current MPs.