New evidence found by BBC News casts further doubt on the Greek coastguard’s version of events surrounding last month’s deadly migrant boat sinking, in which up to 600 people died.

Two survivors have described how the coastguard pressed them to identify nine Egyptians on board as traffickers.

A new video of the overcrowded boat foundering at sea also challenges the Greek coastguard’s account.

It was taken when the boat was said to be on a “steady course”.

BBC Verify has confirmed the footage was filmed when the coastguard claimed the boat was not in need of rescue – and was in fact filmed by the coastguard itself.

We have also confirmed that the larger vessel in the background is the oil tanker Faithful Warrior, which had been asked to give supplies to the migrant boat.

The official Greek coastguard account had already been challenged in a BBC Verify report – but now we have seen court documents which show serious discrepancies between survivors’ witness statements taken by the coastguards, and the in-person evidence later presented to a judge.

A translator has also come forward with his account of a people-smuggling investigation last year, after another group of migrants were rescued by the coastguard. He describes how witnesses from that incident were intimidated by the coastguard. The legal case collapsed before it could reach trial.

The revelations raise fresh questions about how the Greek authorities handle such disasters.

Both the Greek coastguard and Greek government did not comment and declined our requests for interview.

Soon after the 14 June sinking, nine Egyptian men were detained and charged with manslaughter and people-smuggling.

But two survivors of the disaster say migrants were silenced and intimidated by Greek authorities, after suggesting the coastguards may have been to blame for the tragedy.

For the past month, allegations have been made that the coastguard used a rope to tow the fishing vessel, causing it to sink.

The two survivors we spoke to in Athens – who we are calling Ahmad and Musaab to protect their identities – say that is what happened.

“They attached a rope from the left. Everyone moved to the right side of our boat to balance it,” says Musaab. “The Greek vessel moved off quickly causing our boat to flip. They kept dragging it for quite a distance.”

The men described how they spent two hours in the water before being picked up by the coastguard.

When I ask how they knew it was that amount of time, Musaab says his watch was still working so he could tell.

Once on land, in Kalamata, they claim the coastguard told survivors to “shut up” when they started to talk about how the Greek authorities had caused the disaster.

“When people replied by saying the Greek coastguard was the cause, the official in charge of the questioning asked the interpreter to tell the interviewee to stop talking,” says Ahmad.

Ahmad says those rescued were told to be grateful they hadn’t died.

He says there were shouts of: “You have survived death! Stop talking about the incident! Don’t ask more questions about it!”

The men say they are scared to speak out publicly because they fear they too will be accused like the Egyptians.

“If there was a fair system in place, we would contribute to this case,” says Ahmad.

The men told us they had both paid $4,500 (£3,480) for a spot on the boat. Ahmad’s younger brother was also on board. He is still missing.