Hopes are fading in Beirut that anyone will be found beneath the rubble of a building destroyed in last month’s explosion.
Rescue workers are searching for the third day after sensor equipment detected possible signs of life.
But the rescuers, including Chilean specialists, have not yet found the source of the signal.
Beirut held a minute’s silence on Friday to mark a month since the explosion, which killed almost 200.
Thousands more were injured by the blast, which happened when 2,750 tonnes of ammonium nitrate detonated.
There has been outrage that so much hazardous material was stored unsafely in a warehouse in the city’s port, close to many residential areas.
The Lebanese government’s resignation shortly afterwards failed to pacify protesters, who clashed with police in the city for several nights.
One month on, seven people are still missing, according to Lebanese officials.
What’s happening with the search?
Search efforts got under way after a rescue team from Chile said it had detected possible signs of life under a destroyed building located between the residential districts of Gemmayze and Mar Mikhael.
The rescuers were walking through the area on Wednesday night when their sniffer dog – trained to find bodies – gave a sign that there was a person inside. When they returned on Thursday, the dog went to the same place and gave the same sign. Specialist sensor equipment then detected a pulsing signal in the area.
The head of the Chilean rescue team, Francisco Lermanda, told reporters on Friday that slow breathing had been detected under the rubble at a depth of 3m (9.8ft).
Rescuers dug three tunnels to try to reach the spot where the pulse was detected, he said.
But, he added, it was too soon to know if anyone was “alive or dead” beneath the debris.
Earlier on Friday, rescue co-ordinator Nicholas Saade told the AFP news agency that the pulse had slowed significantly since the previous day. Reporters at the scene said the most recent test detected no signals at all.
Crowds have been gathering to watch the search efforts, hoping for a miracle.
“Search operations have been going on since the day before yesterday but the chances are very low,” the civil defence agency’s operations director, George Abou Moussa, told AFP.
More on the explosion in Beirut