The U.N. High Commissioner for Refugees estimates more than 1,500 people drowned or vanished while attempting to cross the Mediterranean from Africa to reach Europe in 2011, the deadliest year in the region since the agency started keeping the statistics in 2006.
"Our teams in Greece, Italy, Libya and Malta warn that the actual number of deaths at sea may be even higher," UNHCR spokeswoman Sybella Wilkes told reporters in Geneva, Switzerland.
Wilkes said the estimates were based on interviews with migrants who reached Europe, communications from relatives, and reports from Libya and Tunisia from survivors whose boats either sank or were in distress.
There has been a surge of refugees trying to reach Europe since pro-democracy protests began in North Africa and the Middle East early last year.
Wilkes said her office has learned one of three boats that attempted the Mediterranean crossing this year is missing at sea.
The agency said 56,000 migrants/refugees landed in Italy last year, with 1,574 more reaching Malta and 1,000 landing in Greece. Meanwhile, an estimated 55,000 irregular migrants crossed the Greek-Turkish land border, the agency said.