An estimated 90 migrants are believed to have drowned off the coast of Libya after a smuggler’s boat sunk early on Friday, leaving three survivors and 10 bodies washed up on shore, the International Organisation for Migration (IOM) said.

Survivors told aid workers that the majority of migrants on board were Pakistanis, who are forming a growing group making the journey to Italy, IOM spokeswoman Olivia Headon told reporters at the UN in Geneva.

“They have given an estimate of 90 who drowned during the capsize, but we still have to verify the exact number of people who lost their lives during the tragedy,” she said.

“We are told that two survivors swam to shore, and one person was rescued by a fishing boat,” Headon said. “We are working to get more details on the [capsizing] and where the survivors are so that we can assist them better.” She added early suggestions were that the boat had become unstable.

Headon also said an increasing number of people trying to cross the Mediterranean to Italy and Europe through Libya are Pakistani. Pakistanis were the 13th largest nationality represented amid migrants making the journey last year, but the third-largest nationality in January.

Headon said the reason for the growing movement of Pakistanis is not clear, nor whether the increased flow is expected to continue, but said: “We’re looking into it”.

IOM says over 6,000 people crossed the Mediterranean in January, about two-thirds of them to Italy – an increase of 10 per cent from the previous year. Around 250 people died while making the trip during January.

EU countries have argued over both lowering migrant numbers and determining which countries should be accountable for migrants on arrival.

The EU made a deal with the Libyan coastguard last year to help divert migrants back to Libya.

Aid agencies and the UN have accused European governments of making a “horrific” and “inhumane” deal with Libya.