Libya’s coastguard intercepted about 400 Europe-bound migrants off the country’s coast in the past two days, the UN migration agency said on Monday.
Safa Msehli, a spokeswoman for the International Organisation for Migration, said the illegal migrants were taken to the Al Nasser detention centre in the town of Zawya, west of the capital Tripoli.
Ms Msehli said departures from Libya had increased, which is “especially worrying amid a sharp decrease in search and rescue capacity”.
The UN refugee agency in Libya said two people had died from the 315 migrants who were intercepted in the Mediterranean and returned to Tripoli early on Monday. Their bodies were recovered.
Italian police on Sunday corrected a report that a record 400 migrants had landed on a beach in Sicily, saying the number was about 70, the Ansa news agency reported.
A single wooden fishing boat about 10 metres long was found on the beach near the southern Sicilian city of Agrigento, and a coastguard search backed by a helicopter failed to find the much larger vessel for which they were searching at sea.
Witnesses had earlier told security forces that hundreds of migrants had arrived aboard two boats.
The mayor of the nearest village spoke to some of the migrants and said about 300 might have arrived, and that they were probably all Tunisians.
The migrants had left the beach in small groups, setting off across the island, local press reported.
Some stopped motorists to ask for water or for a ride, the Agrigento Notizie said.
It has been years since arrival figures in the hundreds have been recorded in a single day in Sicily, with human smugglers increasingly avoiding Italy.
Reacting to the initial reports, the anti-immigration League party of Matteo Salvini said: "Italy has become a refugee camp again."
Smaller groups, mostly from Libya, are frequent arrivals.
Italian authorities said 52 people, mainly from Sub-Saharan Africa, arrived on Sunday aboard a 10-metre boat on the small island of Linosa, near Italy's southern-most island, Lampedusa.
Interior Ministry figures from Friday show 4,445 migrants have arrived in Italy since the start of the year.
Libya is a major transit point for migrants and refugees fleeing war and poverty in Africa and the Middle East for the relative safety of Europe.
Most migrants make the perilous journey across the Mediterranean in ill-equipped and unsafe rubber boats.
The IOM said last month that its estimated death toll among migrants who have tried to cross the sea since 2014 had passed 20,000.
Since the outbreak of the coronavirus, major maritime rescue charities such as Ocean Viking and Sea-Watch have suspended migrant rescue operations.
Travel disruptions have also forced the UN’s refugee and migration agencies to halt their resettlement flights for the most vulnerable people.
The EU has linked up with the coastguard and other Libyan forces to stop the flow of migrants.
But rights groups say those efforts have left migrants at the mercy of brutal armed groups or confined in squalid and overcrowded detention centres that lack adequate food and water.
The EU agreed this year to end an anti-migrant smuggling operation involving only surveillance aircraft.
It said it would send military ships to concentrate on upholding a widely flouted UN arms embargo on Libya.