At least 400 refugees are feared to have drowned in the Mediterranean Sea after their boats capsized on the way to Europe.
Unconfirmed media reports said four vessels carrying mainly Somalis, but also some Eritreans and Ethiopians, capsized near the Egyptian coast.
BBC Arabic spoke to relatives of three people said to be on board one of the boars, and quoted the Somali ambassador to Egypt as saying a team was working to verify the information.
Médecins Sans Frontières tweeted in response to the news: "Mediterranean is a mass grave".
It later added that it could not confirm the reports, however.
BREAKING: Media report that 400 #people have drowned after a boat capsized between # Egypt & Italy. 2016, the Mediterranean is a mass grave.— MSF Sea (@MSF_Sea) April 18, 2016
UPDATE: We cannot confirm news of the shipwreck. Jut sharing this report https://t.co/YOupU2jYV4— MSF Sea (@MSF_Sea) April 18, 2016
Italian President Sergio Mattarella referred to the incident in Rome today, where he said Europe needed to reflect in the face of "yet another tragedy in the Mediterranean in which, it seems, several hundred people have died".
According to the Irish Independent, UNHCR spokesman William Spindler said: "Our offices in Egypt, Italy and Greece are trying to find out more about this reported incident but, so far, we cannot confirm it."
Flavio di Giacomo, a spokesman from the International Organisation for Migration, told IBTimes UK: "We can't exclude it either but at the moment there are no confirmed shipwrecks."
Italy's coastguard has so far said it has no information regarding the possible drowning, but it did say six bodies had been found and 108 people rescued in a separate incident.
A further 33 people were rescued from an island off the eastern coast of Sicily on Sunday, it said.
More than a million refugees and migrants arrived in Europe last year, many of them having made the treacherous journey across the Mediterranean Sea via human traffickers.
Thousands have died making the crossing; Pope Francis warned last year that the Mediterranean was turning into "a vast cemetery". Exactly a year ago today, an estimated 800 people died when their boat capsized off the Libyan coast. The deaths fuelled calls for a stronger response from Europe and prompted a number of summits on the crisis.