At least 90 people, including 11 Pakistani nationals, were feared dead on Friday in the latest migrant tragedy in the Mediterranean Sea off the coast of Libya, the UN migration agency said.

The tragedy happened off the coast of Zuwara in the early hours of Friday, International Organisation for Migration (IOM) spokeswoman Olivia Headon told reporters in Geneva by phone from Tunis.

“At least 90 migrants are reported to have drowned, when a boat capsized off the coast of Libya this morning,” the IOM said in a statement.

The agency said that “10 bodies are reported to have washed up on Libyan shores”, including those of two Libyans and eight Pakistanis.

But Foreign Office (FO) spokesman Dr Mohammad Faisal confirmed that up to 11 Pakistani citizens were among those who drowned.

Faisal told The Associated Press that Pakistani diplomats had reached Libya's coastal area to collect more details. He said that Pakistani authorities will try to bring back the bodies of Pakistanis killed in the tragedy.

See: Envoy details dire state of Pakistani illegal migrants in Greece, seeks urgent action

IOM said its partner agencies are reporting that the capsized boat was carrying mostly Pakistani migrants. But the FO spokesman dispelled the impression that most of the drowned migrants were Pakistanis, saying only 11 Pakistanis died.

Two survivors from the disaster had swum to shore, while another was rescued by a fishing boat, the IOM said.

The agency has repeatedly issued warnings over the extreme dangers facing migrants who try to reach Europe via the so-called central Mediterranean route, which connects Libya to Italy.

IOM said on Friday that more than 6,600 migrants and refugees had already entered Europe by sea this year, with central Mediterranean route crossings to Italy accounting for nearly 65 per cent of the entries.

It voiced surprise that Libyans were among the dead, pointing out that only 29 Libyan nationals were rescued or intercepted trying to cross the Mediterranean in all of 2017, with no Libyan deaths recorded last year.

Asked if it was common to see Libyans among the migrants trying to cross to Europe, IOM spokesman Joel Millman said, “we haven't (really) seen that before.”

“They could have been smugglers,” he told AFP.

The large number of Pakistanis found dead could meanwhile hint at a shift in migration trends.

IOM pointed out that Pakistanis made up the 13th largest group trying to cross the Mediterranean to Europe last year, with 3,138 of them arriving in Italy in 2017, and no recorded sea deaths.

But they have already climbed to third place this year, with an estimated 240 Pakistanis reaching Italy in January, compared to just nine during the same month last year.

16,000 drowned

Drownings in the Mediterranean began surging in 2013 as Europe's worst migration crisis since World War II began picking up speed, with hundreds of thousands of people fleeing war and poverty in the Middle East and elsewhere.

Over the past five years, more than 16,000 people have died trying to make the perilous crossing to Europe, according to IOM numbers.

Excluding Friday's tragedy, 246 migrants and refugees have already died trying to cross the Mediterranean since the beginning of the year, compared to 254 casualties during the first month of 2017.

Two hundred and eighteen of the deaths this year occurred on the central route, IOM said, while 28 happened on the western route that links North Africa to Spain.

No deaths have been recorded this year on the eastern Mediterranean route that connects Turkey and Greece, used by 1,089 migrants so far in 2018.

The EU last year reached controversial agreements with chaos-wracked Libya to stem the flow of migrants from that country, following a more comprehensive deal with Turkey in 2016, which sharply reduced the numbers crossing to Greece.

Casualties in the eastern Mediterranean have dropped dramatically since then.

In the 22 months since the deal with Turkey was reached in April 2016, fatalities on that route have fallen to an average of 6.75 per month, from 96.25 per month during the year prior to the agreement, IOM said.