A general view shows the Beirut silos damaged in the August 2020 port blast, in Beirut, Lebanon May 17, 2022.
A general view shows the Beirut silos damaged in the August 2020 port blast, in Beirut, Lebanon May 17, 2022. Reuters / MOHAMED AZAKIR

Victims of the 2020 Beirut port blast have filed a $250 million claim against U.S.-based firm TGS, their advocates told Reuters on Thursday, saying the company is "liable" for damages caused by ammonium nitrate that detonated in the Lebanese capital.

The extremely explosive chemicals arrived at the Beirut port aboard the Moldovan-flagged Rhosus in 2013 and remained at the port until they blew up on Aug. 4, 2020, killing more than 215 and wounding thousands.

The Rhosus had been sub-chartered in 2012 by seismic study firm Spectrum, which was acquired by geophysical services firm TGS seven years later. Listed in Oslo, the company has operational headquarters in Houston, Texas.

Nine victims of the blast are now suing TGS in a Texas court, saying it was responsible for any "wrongful conduct" by Spectrum, according to a synopsis of the complaint provided to Reuters by Swiss-Lebanese advocacy group Accountability Now.

Accountability Now's Zena Wakim said she hoped the new complaint would reveal details that could revive Lebanon's stalled probe into the blast.

TGS told Reuters it had yet to be formally served but that it denied "each and every allegation raised in the lawsuit, and intend to vigorously defend this matter in court."

It said it carried out its own probe after the blast into Spectrum's behaviour, "which confirmed that Spectrum acted diligently in its conduct of the survey and had no responsibility for the explosion."

Victims, however, say someone must be held accountable.

Tania Daou Allam lost her husband, a naturalized U.S. citizen who had accompanied her to a doctor's appointment in Beirut.

The blast shattered glass windows in the clinic, and large shards sliced through her husband's throat.

"In Lebanon, justice has been delayed for two years and this is an added legal venue for us and for all victims," said Allam, who has also signed up as a plaintiff in the Lebanon probe.

"We cannot ignore the fact that this company has to be held responsible," she told Reuters.

Sarah Copland, whose son Isaac was a U.S. citizen and the youngest person to die in the blast, said she felt a duty to other victims to pursue justice wherever possible.

Copland said any financial awards would be shared among all victims - not just the plaintiffs - to support families in Lebanon struggling with the financial crisis.

"There's no jail term or dollar figure that could make this better," she said.

"If I ever, ever have the opportunity to see Isaac again I want to be able to say, 'I did everything possible to make sure that the people who did this to you were held accountable.'"