A Spanish charity says it has rescued 230 migrants, from African and Asian countries, in boats trying to cross the Mediterranean Sea.

Proactiva Open Arms spokeswoman Laura Lanuza said the group found two boats sailing 90 kilometres (56 miles) from the Libyan coast Thursday.

Two merchant vessels also rescued migrants, mostly from Eritrea, who were trying to reach European shores in two other boats. The migrants were transferred to Proactiva's rescue vessel, the Golfo Azurro, which plans to take them to an Italian port Saturday.

Speaking Friday, Lanuza said there were several minors and 10 women among the migrants, one of them heavily pregnant.

She said there were also migrants from Bangladesh, Cameroon, Pakistan and Togo. She said some needed treatment for burns and other injuries.