An eight-year-old boy drowned in the Mediterranean as thousands of migrants made the perilous voyage to Europe over the Easter weekend.

The Italian coastguard reported launching 19 rescue missions as migrants from Libya attempted to make the trip in rubber dinghies and wooden boats.

Italian authorities say more than 2,000 people were rescued on Friday and 3,000 on Saturday, but at least 20 drowned.

"The sea continues to be a graveyard," Médecins Sans Frontières (MSF) said in a tweet.

Reuters photographer Darrin Zammit Lupi described the scene: "In 19 years of covering the migration story, I have never experienced anything like today."

MSF used its two ship – Aquarius and Prudence – to rescue about 1,000 people in nine boats but video footage showed chaotic scenes as migrants clung on to rafts or slipped into the water.

The number of migrants crossing the Mediterranean is down from its peak in 2015 with nearly 32,000 migrants estimated to have arrived in Europe by sea so far this year. Of that, more than 650 have died.

The UN said 2016 was the deadliest year on record in the Mediterranean sea even though the number of migrants making the trip was down on the year before. Arrivals in Italy increase during May and usually peak in July when conditions at sea tend to be better.