Thirty people are missing and 17 have been rescued in the central Mediterranean after the boat in which they were travelling from Libya capsized in bad weather.

Rescue operations were ongoing, supported by merchant ships and aerial support by the EU’s border agency Frontex, while two further merchant vessels were en route to the area, Italy’s 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 northwest of Benghazi.

Alarm Phone, another charity that picks up calls from migrant vessels in distress, said on Twitter it had first alerted authorities on Saturday, emphasising the boat, which was carrying 47 people, needed immediate rescue.

After an initial rescue attempt by a merchant ship failed due to bad weather, Libyan authorities asked Rome for help given they lacked the means to carry out the rescue, the coast guard said in the statement.

Rome then requested merchant ships in the area to join the rescue efforts.

However, the migrant vessel turned over during an attempt to transfer the people onto the “FROLAND” merchant ship on Sunday morning, it said.

Italy’s coast guard said on Sunday the capsize occurred outside Italy’s Search and Rescue area (SAR).

However, Rome’s ability to rescue migrants at sea has come under scrutiny following a February 26 shipwreck near the southern region of Calabria, in which at least 79 died.

On Saturday the coastguard said more than 1300 migrants had been rescued in three separate operations off the southern tip of Italy, with a further 200 saved off Sicily.

The number of migrant arrivals in Italy has been on the rise, piling pressure on the country’s conservative government, which took office last October promising to cut the flow only to see a sharp increase in such landings this year from both North Africa and Turkey.

Some 17,600 people had reached Italy this year as of March 10, compared to 6000 in the same period last year.

Hundreds have also died trying to cross the Mediterranean and reach Europe.

– AAP