The migrant rescue ship Ocean Viking has saved 153 people in distress in Malta's search and rescue zone, the French charity SOS Mediterranee operating the vessel said Saturday.

The rescue operations in the central Mediterranean on Friday were coordinated by Italian maritime authorities, it said.

The rescues, which followed in quick succession, involved 59 and 65 people travelling on two wooden boats. Later, 29 people were plucked off a fibreglass vessel after another distress signal.

The migrants had been at sea for five days, and went without food and water for two days, it said, adding they were severely dehydrated.

Another 15 migrants were rescued in the same area on Thursday.

The Ocean Viking has been instructed to disembark the migrants in Civitavecchia, a coastal town nearly 1,000km away. It should take the ship around three days to reach the port. 

Maltese authorities have largely ignored calls for help from migrant rescue vessels. 

The new Italian government, which campaigned on a promise to "stop arrivals", says charity vessels in the area sail under the flags of specific countries -- namely France and Germany -- which consequently have a duty to take in some of those rescued. 

According to the Italian interior ministry, nearly 90,000 people have arrived by sea so far this year, but only a fraction have been taken in by France and Germany.

The migrants rescued by charity vessels make up just 14 per cent of arrivals over the past 12 months, according to Matteo Villa from the Institute for International Political Studies.