Fewer than 100 migrants have lost their lives crossing the Mediterranean since the EU boosted its search and rescue operations at the end of April.
In comparison, 1200 people died in a single week in mid-April, before the arrival of extra naval resources to patrol the coast of Italy, Amnesty International said.
The human rights group said the "dramatic" fall in migrant deaths proved the value of Operation Triton, the search and rescue operation run by the EU border control agency Frontex.
One in 16 people attempting the crossing died in the first four months of 2015 before the emergency measures. This figure has fallen to one in 427 in the past two months.
At an emergency summit on April 23, the European Council agreed that it would triple the funding for operations in the Mediterranean. EU member states pledged to provide additional vessels and aircraft to help avoid further tragedies at sea. Since then, 99 people have died.