Following the deaths of Marie Colvin of the Sunday Times and Remi Ochlik, a freelance French photographer, there have been claims that they were deliberately targeted, including an allegation by the French president, Nicolas Sarkozy, that they were "assassinated" in an attack that injured several other journalists.

What is the evidence that they were deliberately fired on?

Most of the evidence of a deliberate attack comes from French journalist Jean-Pierre Perrin, who was also in the Homs suburb of Bab Amr. He described in Liberation how the house being used as a press centre had been "evacuated" after being targeted before. According to Perrin, evidence of this was also visible in the fact that its satellite antenna had been hit many times by snipers. He also described how the journalists in the city were warned several days before the fatal incident that they would be killed if they were caught, as well as suspicions that their communications may have been intercepted and their reports read by the regime.

In a separate interview, Perrin also told the Telegraph: "A few days ago we were advised to leave the city urgently and we were told: 'If they [the Syrian army] find you, they will kill you'. I then left the city with [Colvin] but she wanted to go back when she saw that the major offensive had not yet taken place." He added his view that the Syrians were "fully aware" that the press centre was broadcasting direct evidence of crimes against humanity, including the murdering of women and children.

Is there any other evidence that the regime is targeting those involved in telling the story in Homs?

As well as Colvin and Remi, a prominent citizen journalist, Rami al-Sayyed, was also killed the day before. In addition, a group of activists trained by the organisation Avaaz, including several medical volunteers attempting to reach the press centre and two other citizen journalists, were found executed with their hands tied near Bab Amr after trying to reach the injured and dead reporters.

CNN staff, who had used the same media centre in an earlier visit to Homs, have indicated that they believe the Syrian military targeted their dishes on the roof with artillery fire.

The Committee to Protect Journalists has said the Assad regime appears to have a policy of intimidation against journalists to enforce a news blackout, a policy it believes has become more violent. It claims: "By controlling local news reports and expelling or denying entry to dozens of foreign journalists, the Syrian government has sought to impose a blackout on independent news coverage since the country's uprising began almost a year ago, CPJ research shows. But along with the intensity of the conflict, the dangers to the press have risen dramatically in recent months – both for independent citizen journalists and the international journalists who have smuggled themselves into Syria at extremely high risk."

Is there any physical evidence of a direct attack?

The journalists were in an area that was being subjected to indiscriminate fire and rocket fire, which can be extremely inaccurate. Activists, however, claim that since landlines into the city were cut, Syrian forces have been firing deliberately on locations where there was a mobile or satellite signal – a claim it is not possible to verify.