Medics carry a survivor on a stretcher, after a boat carrying dozens of migrants sank in international waters in the Ionian Sea, at the port in Kalamata town. AFP

As many as 750 men, women and children from Syria, Egypt, the Palestinian territories and Pakistan were on board the vessel, trying to reach relatives in Europe.

The Greek coast guard has defended its response to the tragedy that left more than 500 migrants presumed drowned. The vessel sank on Wednesday.

Shahbaz expressed his grief over the tragedy and said Monday would be observed as a day of mourning, with the national flag flying at half-staff. He previously said that Pakistan’s embassy in Athens has identified 12 nationals who were rescued by the coast guard.

Scores of people onboard a boat during a rescue operation, before their ship capsized on the open sea, in Greece. AP

There was no official information on how many Pakistanis were onboard the vessel, how many survived or how many perished.

Greek authorities have been criticised for their failure to act more quickly. They say the migrants insisted they didn’t need any help, but non-governmental organisations say they received a number of calls for help. The sinking was one of the worst disasters of its kind this year.

Local official Chaudhry Haq Nawaz said there was still no confirmation on how many young men from the area were onboard the ill-fated boat, or how many are among the dead or missing.

He said efforts are underway to collect relatives’ DNA and the test results will be sent to Greece to help identify victims. People have been offering their support to relatives of those presumed to have been on the boat.

Raja Sakundar, of Bindian village in Kotli, said his four nephews aged 18 to 36 remain missing. “We were informed by the media (of the tragedy). When children are not found or die, you can understand what a parent goes through,” he said.

Raja Muhammad Majeed asked the Pakistani government to bring back his nephew, Raja Awais. “If he is dead, bring back (the) body,” he said. “When we bury him here, his mother, sisters and others can go to his grave and offer prayers. We will be patient.”

Before 21-year-old Pakistani Muhammad Akash boarded a rickety fishing trawler in Libya on a journey he hoped would take him to a brighter future in Europe, he contacted his family one last time.

“He made a heartfelt phone call to his brother, urging the family to pray for him as he embarked on what he acknowledged to be a perilous journey,” his uncle Amanat Ali told reporters on Sunday after learning Akash was one of hundreds who drowned off the coast of Greece on Wednesday.

Four of Akash’s friends from the town of Khuiratta were also aboard, but only two survived. They had the grim task of breaking the news to his family. The uncle told reporters that Akash started his journey three months ago.

He had been in regular contact with two other friends who had already made their way to Italy by similar means, and he wanted to follow them.