Story highlights Nearly 900 migrants have died at sea trying to reach Europe in past week alone, U.N. says

Increasingly busy Libya-Italy route is much more dangerous than Turkey-Greece route

(CNN) More than 2,500 migrants have drowned in the Mediterranean while attempting to cross into Europe so far this year, the U.N. Refugee Agency says, with at least 880 drowning in the past week alone.

"Thus far 2016 is proving to be particularly deadly," said William Spindler, spokesman for the agency, in announcing the soaring death toll in Geneva Tuesday.

He said 2,510 people have died making the perilous crossing so far this year, compared to 1,855 in the first five months of 2015 -- an increase of 35%. Fewer than 60 died in the same period in 2014.

At least 880 migrants drowned in a series of sinkings and wrecks in the past week, said Spindler, citing new information from survivors who reached Italy.

Photos: Italian Navy saves migrants after boat overturns Photos: Italian Navy saves migrants after boat overturns A ship crowded with people fleeing conflict in the Mideast flips onto its side Wednesday as an Italian navy ship approaches. Five people died and 500 were rescued. Hide Caption 1 of 10 Photos: Italian Navy saves migrants after boat overturns The ship was spotted Wednesday off the Libyan coast. Many people fleeing the Mideast on boats head to Italy. Hide Caption 2 of 10 Photos: Italian Navy saves migrants after boat overturns Migrants cling to the hull of the ship and float in the water as Italian sailors rescue them with life rafts. Hide Caption 3 of 10 Photos: Italian Navy saves migrants after boat overturns Italian sailors prepare to toss floatation devices into the water from their ship. Hide Caption 4 of 10 Photos: Italian Navy saves migrants after boat overturns A migrant uses a buoy to stay afloat in the water. Hide Caption 5 of 10 Photos: Italian Navy saves migrants after boat overturns Migrants climb a ladder to the deck of the Italian navy ship. Hide Caption 6 of 10 Photos: Italian Navy saves migrants after boat overturns Thousands of migrants have died in the Mediterranean when their ships broke up or capsized. Hide Caption 7 of 10 Photos: Italian Navy saves migrants after boat overturns The migrants are helped on board the ship after their own vessel sank. Hide Caption 8 of 10 Photos: Italian Navy saves migrants after boat overturns An Italian helicopter assisted in the rescue at sea. At least seven people died but 500 were rescued. Hide Caption 9 of 10 Photos: Italian Navy saves migrants after boat overturns The helicopter hovers above the water during the rescue operations. Hide Caption 10 of 10

He said that on top of three major sinkings of overcrowded vessels from Libya that occurred Wednesday Thursday and Friday, officials had subsequently learned that 46 were missing from a raft carrying 125 people that deflated, eight had been lost overboard from another and four died in a fire on board another.

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