The death of several hundred migrants on Saturday night was a “man-made tragedy” that could well have been avoided, Amnesty International said.

“What we are witnessing in the Mediterranean is a man-made tragedy of appalling proportions. These latest deaths at sea come as a shock but not a surprise,” John Dalhuisen, Amnesty International’s director for Europe said.

Mr Dalhuisen lamented the lack of an adequate search and rescue operation in the Mediterranean adding that while merchant vessels and their crews had bravely attempted to fill the gap left by the chronic shortfall they were not designed, equipped or trained for maritime rescue.

“It is time for European governments to face their responsibilities and urgently set up a multi-country concerted humanitarian operation,” he said.

The UN High Commissioner for Refugees, António Guterres, expressed his shock at the hundreds of lives lost.

“Should these numbers be confirmed, the incident – which happened overnight – will be the largest loss of life in any incident in the Mediterranean involving refugees and migrants,” he said.

The tragedy follows an incident only last week in which 400 lives were lost.

Mr Guterres said this weekend’s tragedy had highlighted the need for a comprehensive European approach to address the migration flow.

Migrant Offshore Aid Station (MOAS) said thousands more men, women and children would die in the coming weeks unless more rescue assets were deployed immediately to the Mediterranean.

It said it would redeploy its own rescue operation on May 2 after saving some 3,000 lives in 60 days last year.