Documentary on war correspondent Marie Colvin claims she died in 'deliberate attack' on journalists by Assad regime

• Video report by ITV News International Affairs Editor Rageh Omaar

Marie Colvin was one of the UK's most respected war reporters, fearlessly chronicling lives of ordinary people caught up in some of the worst conflicts of our times.

The American-born British journalist was killed covering the siege of Homs with photojournalist Paul Conroy in the early days of Syria's civil war.

Her death made headlines around the world, and many said it was a deliberate attack on international journalists by the Assad regime.

Colvin's extraordinary life, and the circumstances surrounding her death, are the subject of a new documentary, Under the Wire, based on Conroy's book.

The 56-year-old was killed alongside French photographer Remi Ochlik when a rocket slammed into the ground by the front door of the makeshift media centre, sending shrapnel and splinters tearing through the building.

The film claims the media shelter housing Colvin, Conroy and other journalists was, specifically and methodically targeted.

Speaking to ITV News before a screening of the documentary, Conroy, who survived the attack, described the moment they came under attack.

"We were just going into the main room in the media centre when I heard two huge explosions about 100 metres either side. Less than a minute later, two more huge explosions, about 50 metres," he said.

"And at that point I knew that this was quite precise. And they were bracketing and walking the shells into our building.

"And a minute after that we took four direct hits on the building."

Conroy says that it was the forgotten people that drove Colvin's fierce determination to report the horrors of war.

He said: "Her thing were the people at the sharp end of the stick where the not-so-smart bombs and bullets always land. The women and the children. And that's what drove her."

The family has brought a case against Assad. Cat Colvin, Marie's sister, said one of the main reasons behind the decision to hold the Syrian leader accountable was to reassure the people of this war-torn country, they "had not been forgotten".

"I want them to know that my family appreciates their respect for Marie," Colvin told ITV News.

Six years on from Marie Colvin's death, the final battle in the long Syrian war is poised to bring the conflict to an end in what could be the bloodiest episode yet as Assad forces are set to launch an assault on the last rebel stronghold of Idlib.

But this time, the people of Idlib will alone bear witness to the battle, with no journalists to capture the horror.

"These tyrants, these regimes, they love to work in the dark," Conroy said.

"And that's what Marie did well, she shone light into those dark places."