New evidence have cast doubt on the Greek coastguard’s account of Wednesday’s migrant shipwreck in which hundreds including scores of Pakistanis are feared to have dies.
According to a BBC investigative report, analysis of the movement of other ships in the area suggests the overcrowded fishing vessel was not moving for at least seven hours before it capsized.
The Greek coastguard still claims that during these hours the boat was on a course to Italy and not in need of rescue.
Greek authorities have not yet responded to the BBC's findings.
At least 78 people are known to have died, but the UN says up to 500 are still missing.
The UN has called for an investigation into Greece's handling of the disaster, amid claims more action should have been taken earlier to initiate a full-scale rescue attempt.
Greek officials maintain those on board said they did not want help and were not in danger until just before their boat sank.
The BBC has obtained a computer animation of tracking data provided by Marine Traffic, a maritime analytics platform.
Their data shows hours of activity focused on a small, specific area where the migrant boat later sank, casting doubt on the official claim it had no problems with its navigation.
The fishing boat had no tracker so is not shown on the map. Neither are coastguard and military vessels which do not have to share their location. Timeline of official coastguard account challenged
Frontex, the EU's border force, says it first spotted the migrant boat at around 08:00 GMT on Tuesday and informed the Greek authorities.
Alarm Phone, an emergency hotline for migrants in trouble at sea, say they received a call at 12:17 GMT saying the boat was in distress.
We have used video and photographs authenticated by BBC Verify, as well as court records and shipping logs, to analyse the movement of vessels in the area in the following hours.
The Marine Traffic animation shows a ship called the Lucky Sailor abruptly turning north at 15:00 GMT.
The owner of the Lucky Sailor gave us its log book and confirmed it had been asked by the Coastguard to approach the migrant boat and give food and water.