KARACHI: At least 209 Pakistanis were on an overloaded boat that capsized and sank in open seas off Greece last week, according to data shared with Reuters on Thursday by a Pakistani investigative agency.

The figure of 209 is based on information provided by families who came forward to say a relative of theirs had boarded the boat heading from Libya towards Greece and were still missing, the Federal Investigation Agency (FIA) said.

The official death toll from the accident still stands at 82 and the number of survivors at 104, of whom 12 were Pakistanis.

"An investigation to verify this is underway," FIA Islamabad Zone Director Rana Abdul Jabbar told Reuters.

The FIA has been tasked by the Pakistan government with handling investigations into the tragedy.

Hundreds of people from different countries are believed to have been on board the vessel, in what is seen as the worst sea disaster in years for the region.

Pakistan is yet to officially confirm how many of its citizens were on the boat, but kick-started a DNA sampling effort to help Greece identify those who died.

The data shared by the FIA showed that 181 people were from Pakistan and 28 from Pakistan-administered Kashmir. Officials gathered the DNA samples from 201 families.

Witness accounts suggested that between 400 and 750 people had crammed onto the 20- to 30 metre-long (65- to 100-foot) fishing boat which then capsized and sank early on June 14 about 50 miles (80 km) from the southern coastal town of Pylos.

The FIA said 29 suspected human smugglers had been arrested in Pakistan so far over the case.

Greece has charged nine Egyptian men over the shipwreck, the worst in the Mediterranean Sea this year, and placed them in detention pending trial. The accused deny any wrongdoing.