The non-governmental organisation Proactiva Open Arms picked up a rubber dinghy carrying 134 people, including seven children, on Monday night. They were to be transferred to the Aquarius rescue ship operated by another NGO, SOS Mediterranee, before being taken to Pozzallo in Sicily.
A military ship from the European anti-smuggling operation Sophia also rescued 121 people aboard two other boats, the coastguard said.
According to the Italian daily La Repubblica, smugglers have lowered the price of a crossing to €400 ($475) per person, in part due to the bad winter weather, but they are still cramming as many migrants as possible into the dinghies.
In his traditional Christmas address on Monday, Pope Francis urged people around the world not to forget the plight of migrants, who had been "driven from their land" because of leaders willing to shed "innocent blood".
No-one should feel "there is no room for them on this Earth," Francis told tens of thousands of worshippers gathered at the Vatican for his traditional "Urbi et Orbi" Christmas message.