Up to 750 men, women and children from Syria, Egypt, the Palestinian territories and Pakistan were on board the vessel trying to reach Europe.

More than 500 people are presumed to have drowned when the vessel sank on Wednesday.

Local media has reported that at least 298 Pakistanis died, 135 from the Pakistani side of Kashmir.

To date 104 survivors have been rescued and 78 bodies have been recovered.

The Ministry of Foreign Affairs has confirmed that 12 Pakistanis were among the survivors. A total from 310 people were on board.

No survivors or bodies have been found since the day of the accident.

Pakistan's prime minister Shehbaz Sharif has said Monday will be observed as a day of mourning with the national flag flying at half-mast.

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There was no official information on how many Pakistanis were onboard the vessel or how many died.

Mr Sharif has also ordered a "high-level inquiry" to "ascertain facts in the wake of the tragic incident".

He added that "law enforcement agencies have been tasked to tighten the noose around the individuals involved in the heinous act of human smuggling".

"I have also directed Pakistan Foreign Office to undertake immediate coordination at all levels to collect information about the missing people and keep the nation updated," he added.

"I assure the nation that those found negligent towards their duty will be held to account. Responsibility will be fixed after the inquiry and heads will roll."

Meanwhile, families in the village of Bindian in Pakistan-controlled Kashmir are still in limbo about the whereabouts of their loved ones.

'Bring back the body'

Raja Sakundar said his four nephews aged 18 to 36 remained missing.

He said: "We were informed by the media (of the tragedy). When children are not found or die, you can understand what a parent goes through. What is happening to us? We have no information whether they are alive or dead."

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."

The Greek coastguard has defended its response to the tragedy after it was criticised for failing to act more quickly.

They said the migrants insisted they did not need any help, but non-governmental organisations said they received a number of calls for assistance.

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Meanwhile, police in Pakistan-administered Kashmir said on Sunday that they had arrested 12 people involved in sending local youths to Libya for the onward journey to Europe.

Senior officer Khalid Chauhan said police had picked up the suspects in a crackdown on human traffickers.

Police were interrogating them for their alleged roles in luring, trapping and sending locals abroad after extracting huge amounts of money from them.

Around 28 people from the Koi Ratta area in the district of Kotli had gone to Libya for onward travel to Europe, police said.

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 were among the dead or missing.

He said efforts were under way to collect relatives' DNA and the test results would 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.