Hundreds of Pakistanis are believed to have been on the vessel that sank off the coast of Greece earlier this week, but just 12 have been accounted for. Pakistani Prime Minister Shehbaz Sharif declared Monday a national day of mourning to remember the victims of the boat that capsized off the coast of Greece. Between 500 and 700 men, women and children from Syria, Egypt, the Palestinian territories and Pakistan are believed to have boarded the vessel when it capsized and sank. The sinking was one of the worst disasters of its kind this year on the Mediterranean Sea, with some 78 bodies recovered on the water, 104 rescued alive, and hundreds missing or feared dead. "Pakistan will observe June 19 as a day of mourning and the national flag shall fly on half-mast," Sharif said on Sunday, expressing his grief over the tragedy  Pakistan's Embassy in Athens said it had identified 12 of its nationals rescued by the coast guard. Although there was no official information on how many Pakistanis were onboard the vessel, local media reports suggested the number could be in the hundreds. The distressed boat had set off from Libya en route to Italy when it was spotted by the Greek Coast Guard. Questions have arisen about whether the Greek coast guard should have done more, as it was in contact and close to the vessel in its final hours Noraie-Kia, the head of migration policy for Europe at the Heinrich Böll Foundation, told DW that the reason why the ship was headed to Italy was "a result of Greece repeatedly committing illegal border violations and so-called pushbacks."  "What we have been witnessing for years is a policy of border securitization that indeed leads to more deadly shipwrecks," Noraie-Kia added.  Crackdown on human traffickers In response to the tragedy, the Pakistani government ordered a crackdown on human traffickers, who are believed to be luring people on perilous journeys to Europe via Libya and the Mediterranean. A special committee is expected to set up a legal framework and boost international coordination to prevent such incidents and punish traffickers, the prime minister's office said in a statement. Traffickers are said to make millions each year off young Pakistanis seeking to reach Europe, but hundreds of them either die or end up in prison midway through the journey. Meanwhile, officials said nine people had been detained in Pakistan-administered Kashmir, where the majority of the victims originated, and one in Gujrat, a city known for its numerous migrant departures. "They are presently under investigation for their involvement in facilitating the entire process," said Chaudhary Shaukat, a local official from Pakistan-administered Kashmir. Greek coast guard captain defends himself In the aftermath of the tragedy, the Greek coast guard has been under fire for its role in the incident, accused of not doing enough to save the migrants, after one of its boats spotted the vessel in distress prior to its sinking. One coast guard captain, whose identity was not revealed, defended himself to Greek media. "We approached the vessel to check its condition and that of the passengers and again offered assistance," the Greek captain said, adding that when officials tied a rope to the bow of the ship, those on board shouted "No Help" and "Go Italy," the report stated. "Despite repeated appeals as to whether they needed help, they ignored us and untied the rope at around 11:57 p.m. (2057 GMT). They started the engine and headed west at low speed," the report added. According to conflicting reports, which could not be verified by AP and Reuters, people on board had reached out to activists to seek help, describing a situation of deep distress on the boat. Activists say the migrants made repeated pleas for help more than 15 hours before the vessel sank. International maritime law and coast guard experts have said that conditions on the vessel clearly showed it was at risk, and should have prompted an immediate rescue operation, regardless of what the boat's occupants may have said.