Aid workers said on Friday they recovered 117 bodies that have washed up on Libyan shores, as Greek rescuers pulled 340 people and four corpses from a capsized migrant boat south of Crete.
The casualties added to the death toll from last week, the deadliest to date this year. According to the International Organization for Migration (IOM), 1,083 migrants lost their lives or went missing in Mediterranean Sea crossings in the May 25-30 period.
The boat - carrying migrants of undetermined nationality - capsized 75 nautical miles (139 kilometers) south of Crete in the central Mediterranean.
"The main question is how many people were on the 25-metre cutter," a Greek Coastguard officer told dpa in Athens as the rescue operation was winding down.
Greek media reported that around 700 may have been on board - meaning that some 360 people were unaccounted for - and speculated that the sunken boat was on its way from Egypt to Italy.
Most of the 241 rescued migrants were being taken to Italy, after a freighter picked them up. Others were on vessels bound for Egypt, Malta and Turkey, Greek state TV ERT said quoting the Crete coastguard.
"Vessels following that route normally pass through that stretch of sea," Flavio Di Giacomo, a spokesman in Rome for the International Organization for Migration (IOM), told dpa.
The Italian coastguard issued a statement suggesting that coordination problems may have hampered rescue efforts.
It said it received the first report about the migrant vessel at 5:15 pm (1515 GMT) on Thursday from an Italian cargo ship that spotted it at the juncture between Greek and Egyptian search and rescue waters.
Italian authorities alerted counterparts in both countries, but Egypt declined to intervene "considering the position of the boat to be beyond its area of its responsibility."
Greek authorities were then urged to take over control of rescue efforts, while Rome issued an SOS appeal to ships passing nearby. Four responded. One reported the capsizing of the migrant boat at 7:20 am, the Italian coastguard said.
In Libya, the dead bodies washing up on shores near the port of Zuwarah were retrieved by Libyan Red Crescent volunteers on Thursday, Stephen Ryan, a communication officer for the Red Cross and the Red Crescent wrote on Twitter and confirmed to dpa.
A local official from the Libyan Red Crescent, Murad Ghariba, told dpa that "most of [the dead] are from sub-Saharan African countries."
Migrant Report, a migration news website, added that "most of the cadavers presented signs of advanced decomposition" and were believed to be of "migrants who perished in a string of shipwrecks that took place inside Libyan waters late last week."
According to IOM estimates, a total of 205,509 have crossed the Mediterranean since the start of 2016, and 2,443 migrants died or went missing, including 1,083 in the May 25-30 period.
Following the March closure of the Balkan route passing through Greece, which was the main gateway to Europe in 2015-16, most migrants and refugees now depart from Libya, and to a smaller extent, Egypt.
Out of the nearly 48,000 migrants who landed in Italy in January-May 2016, the largest proportion - 6,070 - came from Eritrea, Di Giacomo said. Among the other most common nationalities, there were 5,967 Nigerians, 3,882 Gambians and 3,450 Somalis.
The IOM spokesman also said there were more than 7,500 minors among the arrivals - most of them unaccompanied - and that inflows from Egypt were sharply up, from 243 in January-May 2015 to 1,815 in the same period of 2016.