The boat carrying 47 people was travelling in the direction of Italy and capsized 177km (110 miles) north of Benghazi.
Rescue operations were ongoing, supported by merchant ships and aerial support by the European Union’s border agency Frontex, while two further merchant vessels were en route to the area, the coast guard said in a statement on Sunday.
Earlier on Sunday, the Mediterranea Saving Humans charity had tweeted that according to several sources, the vessel, travelling in the direction of Italy, had capsized about 177km (110 miles) northwest of Benghazi.
Alarm Phone – another charity, which picks up calls from migrant vessels in distress – said on Twitter that it had first alerted authorities on Saturday, emphasising that the boat, which was carrying 47 people, needed immediate rescue.
🆘! 47 lives at risk in the Central Med!
Alarm Phone is contact with 47 people in a boat adrift who fled from #Libya. Weather is extremely dangerous and immediate rescue is needed!! pic.twitter.com/w45b5mIzdI
— Alarm Phone (@alarm_phone) March 11, 2023
After an initial rescue attempt by a merchant ship failed due to bad weather, Libyan authorities asked Rome for help given that they lacked the means to carry out the rescue, the coast guard’s statement added.
Rome then requested merchant ships in the area to join the rescue efforts, noting that the capsize occurred outside Italy’s search and rescue area.
However, the migrant vessel turned over during an attempt to transfer people onto the “FROLAND” merchant ship on Sunday morning, it said.
Mediterranea’s head of mission Luca Casarini told the Reuters news agency that four merchant vessels were still in the area.
Italy’s capabilities to rescue refugees and migrants at sea have come under scrutiny following a February 26 shipwreck near the southern region of Calabria, in which at least 79 people died.
Italy’s government is facing a backlash after sharp criticism that it failed to intervene in time to save the passengers.
On Saturday, the coastguard said that more than 1,300 migrants and refugees had been rescued in three separate operations off the southern tip of Italy, with a further 200 saved off Sicily.
Earlier Sunday, Alarm Phone tweeted that three merchant vessels were at the scene, but said it did not know if a rescue operation was under way because it had lost contact with the boat.
A previous tweet from Alarm Phone said one of the vessels, the Basilis L, was monitoring the boat while it awaited the arrival of the Libyan coastguard, “to force the people back to Libya where they had tried to escape from”.
SeaWatch, a German NGO, tweeted Saturday that its surveillance plane had spotted the migrant boat that was “dangerously overcrowded and in frightening waves”.
Only 17 of the people in this picture were rescued by a merchant vessel, and 30 are missing. The case was known to the authorities for over 24 hours. They just knowingly let them drown. pic.twitter.com/du5qTP6WBA
— Sea-Watch International (@seawatch_intl) March 12, 2023
Nearby was “a merchant vessel that was ordered by the Rescue Coordination Center in Rome to coordinate with the Libyan coastguard,” it said.
About two hours later on Saturday, SeaWatch tweeted again, reporting “While the weather is deteriorating and making intervention difficult, Tripoli claims it is unable to send a patrol boat.”
“Many times in the past Italian authorities have coordinated a rescue in this area. We ask that the same be done, avoiding new deaths.”