Rescue teams kept up their search for survivors in Beirut Saturday even as hopes raised by sensor readings of a pulse beneath the rubble of last month's blast began to fade.

The cataclysmic August 4 explosion in the port of Beirut killed at least 191 people, making it Lebanon's deadliest peacetime disaster. One month on, seven people are still listed as missing.

On Wednesday night, a sniffer dog deployed by Chilean rescuers detected a scent beneath a building in the heavily damaged Gemmayzeh neighborhood adjacent to the port.

High-tech sensors confirmed an apparent pulse of 18 to 19 beats per minute underneath the collapsed building and rescue teams took up the search. But after three days' work removing piles of masonry, Chilean rescue specialist Francesco Lermanda late Saturday said there was no longer any sign of life under the rubble.

"Sadly today we can say that technically we have no sign of life inside the building," he told the media.

Two female rescue workers on Saturday slipped through a final tunnel to check for any victim in the last air pocket where there could possibly be but found nobody there, he said. Work would, however, continue to make the zone secure and ensure there was no possibility of any victim being left inside, Lermanda said.

In the afternoon, engineer Riyadh al-Assad had said the workers had cleared two layers of rubble and reached a stairway, where they found no one. The civil defense agency's operations director, George Abou Moussa, in the morning said the chances of finding someone alive were "very low."

But civil defense officer Qassem Khater said his team was determined not to give up. "We are not leaving the site until we've finished going through the rubble, even if a new building collapse threatens," he said.

Chilean specialist Walter Munoz in the morning had put the chances of finding a survivor at "two percent." Lebanese officials had played down the chances of anyone surviving so long beneath the rubble. But even the faint hope of a miracle caught the imagination of a country already reeling from the coronavirus pandemic and the country's worst economic crisis in decades.

"I was not aware I needed a miracle that much. Please God, give Beirut this miracle it deserves," said Selim Mourad, a 32-year-old film-maker. Lebanon lacks the tools and expertise to handle advanced search and rescue operations, so they have been supported by experts from Chile, France and the United States.

The Chileans, in particular, have been praised as heroes by many Lebanese on social media, who have compared their expertise with the lackluster performance of what they see as their own absent state. 

The Lebanese army is facing criticism, especially when the search was suspended briefly before midnight Thursday, apparently to find a crane.

Outraged protesters at the site claimed the Lebanese army had asked the Chileans to stop the search. In a reflection of the staggering distrust of the authorities, some protesters donned helmets and started searching, while others tried to arrange for a crane.

"Where's your conscience? There's life under this building and you want to stop the work until tomorrow?" one woman screamed at a soldier.

Members of Lebanon's civil defense team returned after midnight and resumed work.

The army issued a statement Friday in response to the criticism, saying the Chilean team stopped work at 11:30 p.m. because it feared a wall might collapse. It added that army experts inspected the site and two cranes were brought in to remove the wall, after which the search resumed.

Friday, the country observed a minute's silence for the dead.

(With input from agencies)

(Cover photo: A Chilean rescuer uses a sound tracking machine at the site of a collapsed building after getting signals there may be a survivor under the rubble in Beirut, Lebanon, September 4, 2020. /AP)