* Mostly Syrian refugees on board migrant boat - coastguard
* No more bodies, survivors found in ongoing search
* Several rescues made, more on going on Thursday (Adds details from rescues)
By Steve Scherer
ROME, Aug 6 (Reuters) - Hopes faded of finding survivors of the latest Mediterranean boat tragedy, in which an estimated 200 migrants drowned, on Thursday as rescue ships were called to the aid of more migrant boats in the same area.
Vessels from the Italian and Irish navies and humanitarian agency Medecins sans Frontiers (MSF) saved more than 370 people from a capsized boat thought to be carrying up to 600 on Wednesday, the Italian coast guard said.
They recovered 25 bodies but found no more survivors after scouring the waters overnight. Italian vessels continued to search the area on Thursday, a coastguard spokesman said.
Initial reports put about 700 passengers on the overcrowded fishing boat but interviews with survivors - mostly Syrians fleeing their country's civil war - reduced that estimate and the figure could still change.
Seas were very calm on Thursday, perfect conditions to attempt the sea crossing, said a Reuters photographer aboard the privately funded Phoenix, a vessel run by MSF and the Migrant Offshore Aid Station.
The Phoenix was responding to a distress call for a boat carrying about 500 people, he said. The coastguard picked up 381 on Thursday morning, while an Italy navy ship took 101 from a large rubber boat, and the MSF vessel Argos rescued 87, according to their Twitter accounts.
The Italian navy said it was handing out life preservers to "numerous" migrants on yet another boat.
Wednesday's tragedy occurred when the boat flipped over as an Irish rescue vessel approached, probably because desperate passengers surged to one side as they spotted the ship, LE Niamh, on its way to help them.
"What happened here was because the boat was so overloaded, and the conditions were such that the boat started taking on water and it listed to one side, capsized and sank, all in the space of two minutes," Irish Defence Minister Simon Coveney said on Irish state radio RTE on Thursday.
The Irish ship is part of the European Union Triton mission, which was expanded after up to 800 migrants drowned in a shipwreck in April.
LE Niamh is heading toward the Sicilian port of Palermo, where it will arrive on Thursday afternoon with most of the survivors.
The Mediterranean Sea is the world's most deadly border area for migrants. More than 2,000 migrants and refugees have died so far this year in attempts to reach Europe by boat, compared with 3,279 deaths during the whole of last year, the International Organization for Migration said on Tuesday.
SMUGGLERS
People smugglers, mostly based in Libya and charging thousands of dollars for passage, have sent more than 90,000 migrants by sea to Italy so far this year, the UN refugee agency says. Italy took in 170,000 in 2014.
This summer's mass arrivals in both Italy and Greece show Europe's migrant crisis is worsening. Immigrants fleeing violence and poverty at home continue to pour in from Africa and the Middle East.
Many of the newcomers look to move swiftly to wealthier northern Europe, including to Britain from Calais, France.
In Calais, nightly attempts by large groups of migrants to force their way through the rail tunnel linking France and Britain have provoked public anger and severely disrupted the flow of goods between the two countries.
In April, a 20-metre (66-foot) vessel capsized as it approached a merchant ship that had come to its assistance, making it the deadliest shipwreck in the Mediterranean for decades and a symbol of Europe's long-running migrant crisis. (Additional reporting by Conor Humphries in Dublin, Darrin Zammit Lupi aboard the Phoenix, Editing by Angus MacSwan)
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