Almost 100 refugees missing off Libyan coast
"According to information received on Wednesday afternoon, 20 illegal immigrants of African nationalities have been rescued," General Ayoub Qassem, a navy spokesman in Tripoli, told AFP.
"They were on an inflatable dinghy which tore and filled up with water," he said.
Qassem quoted a survivor as telling his rescuers that the boat had set off with 126 people on boat from Garabulli, 70 kilometres (45 miles) east of Tripoli, and went down battered by high waves.
Three women and a child were among the 97 missing, he said.
The United Nations says the perilous journey across the Mediterranean for refugees desperate to reach Europe has so far this year claimed more than 3,800 lives, a record.
On Wednesday, French aid group Doctors without Borders (MSF) said it had found the bodies of 29 people who perished in a pool of fuel and seawater on a crowded dinghy off Libya, probably from suffocation, skin burns or drowning.