BEIRUT, Sept 3 — Rescue workers dug through rubble in a wrecked district of Lebanon’s capital today in search of possible survivors from a mega-blast at the adjacent port one month ago, after scanners detected a pulse.

A sniffer dog used by Chilean rescuers last night responded to a scent from the site of a collapsed building in the Gemmayzeh area, the city’s governor Marwan Abboud told reporters at the scene.

"There could be survivors,” he said, explaining that scanners had detected a pulse, however faint the hope of finding anyone alive more than four weeks after the explosion.

"We hope someone will make it out alive,” Abboud said.

Michel al-Mur of the Beirut fire department also said a pulse was detected about two metres (six feet) below the rubble.

"One person, according to the (thermal) camera, still has a pulse,” Mur said.

The building has completely collapsed as a result of the blast that killed 191 people, wounded more than 6,500 others and destroyed swathes of Beirut.

Seven people are still missing, according to the Lebanese army.

Chilean rescuers, Lebanese civil defence teams and Beirut fire department workers were excavating the site.

Speaking to local broadcaster LBCI, a rescue worker said scanners had picked up a respiratory rate of "19 breaths a minute”.

Lebanon tomorrow marks one month since the blast that authorities say was caused by a shipment of ammonium nitrate left to languish for years at Beirut’s port. — AFP