Syria could have deliberately targeted Western journalists, according to reports in The Daily Telegraph.
Syrian authorities said they were unaware foreign journalists were in the country after an American-born British journalist and a French journalist were killed on Wednesday.
Marie Colvin, a veteran correspondent for the Sunday Times, and French photographer Remi Ochlik were killed after a makeshift media centre in Homs was destroyed by government shells.
According to French journalist Jean-Pierre Perrin reporters had been told they would be "deliberately" targeted by Syria.
"The Syrian Army issued orders to 'kill any journalist that set foot on Syrian soil'," he said. "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'," said the Liberation journalist.
"I then left the city with the journalist from the Sunday Times but then she wanted to go back when she saw that the major offensive had not yet taken place."
But Al Jazeera quoted Information Minister Adnan Mahmoud as telling AFP: "The authorities had no information that the two journalists had entered Syrian territory".
Mahmoud rejected earlier claims by the protest network Avaaz that government forces deliberately targeted the makeshift media centre in the embattled city where the attack took place.
"They were directly targeted," Avaaz said earlier. "When shelling started abruptly this morning, without warning, it was in contravention of all humanitarian law."
Activists say hundreds of civilians have died in Homs, and that close to 9,000 Syrians have been killed since the start of anti-government protests in March 2011.
President Assad claims the violence is the fault of armed terrorist groups, and has resisted calls to end the violence from the United Nations, the Arab League, the European Union and the United States.