Illegal immigrants are seen on the deck of the Libyan Coast Guard's ship in Tripoli, Libya, on Feb. 28, 2021. A total of 181 illegal immigrants were rescued on Sunday by the Libyan Coast Guard off the country's western coast.(Photo: Xinhua)

At least 39 migrants drowned off Tunisia when two boats capsized on Tuesday, the defense ministry said, as numbers risking the dangerous crossing to Europe continue to rise.

Rescuers pulled 165 survivors from the floundering boats out of the sea to safety.

Defense ministry spokesperson Mohamed Zekri said later that the search had been "temporarily suspended due to nightfall and bad weather."

It was not immediately clear what caused both boats to capsize, but vessels leaving the North African coast for Europe are often heavily overloaded makeshift crafts, departing at night even in rough weather to avoid detection from the coastguard.

The defense ministry said 39 bodies had been retrieved, while Tunisian National Guard spokesman Houcem Eddine Jebabli said at least nine women and four children had died.

The boats left shore overnight carrying mainly migrants from sub-Saharan Africa aiming to reach Europe, but they were spotted by the coastguard off the Tunisian port of Sfax, according to the authorities.

2020 saw an upsurge of makeshift boats attempting to cross the central Mediterranean, the deadliest route for would-be migrants to Europe.

Such vessels have continued to take to the sea almost daily in 2021, despite frequent poor weather.

"Departures have continued to rise," said Romdhane Ben Amor, communications officer at the Tunisian Forum for Economic and Social Rights.

Since the beginning of 2021, 94 migrant boats have been intercepted, according to a count kept by his organization.

AFP