The Red Crescent said the migrants – 94 on one boat and 84 on the other – sent out a distress call from off the coast of southeast Tunisia as they headed for the Italian island of Lampedusa. A previous count had said 174 were rescued.
The 178 migrants from Africa were evacuated to the Tunisian port of Zarzis and provisionally lodged in a warehouse.
They were mostly from Somalia, Ghana, Gambia, Sudan and Niger, said Dr Riyadh Belhaj of the Zarzis Red Crescent which took them in, adding that all passengers on the two boats were rescued.
In Italy, coastguards said on Monday they recovered nine bodies from the sea after a boat carrying more than 150 migrants sank off the Libyan coast.
Rescuers managed to save 144 people and were still searching for others after their vessel overturned 128 kilometres off Libya.
Late on Sunday, Italian coastguards said they had rescued a total of 2,782 people over the weekend from the Mediterranean, with good weather prompting an increase in the number of migrant boats.
The precarious security situation in Libya has sparked a rise in boats setting out for Europe from its unpoliced ports carrying refugees fleeing conflict and poverty in the Middle East and Africa.
The UN refugee agency, UNHCR, says that at least 3,500 people died in 2014 out of more than 218,000 migrants who crossed the Mediterranean, making it the most deadly migrant route in the world.