The government is doing everything it "possibly can" to secure the return of journalists trapped in the besieged Syrian city of Homs, International Development Secretary Andrew Mitchell has said.
The International Committee of the Red Cross said it has been unable to enter the city to evacuate injured Syrians and two journalists - including Sunday Times photographer Paul Conroy - wounded in the attack which killed war correspondent Marie Colvin on Wednesday.
"We are doing everything we possibly can. The Foreign Office have been seeking to negotiate with the Syrian authorities. Our ambassador in Damascus is engaged in trying to do just that," he told BBC1's The Andrew Marr Show.
"It is extremely difficult and the conversations are patchy."
Mitchell called on the Syrian regime of President Bashar al Assad to allow international aid agencies into the city and the embattled neighbourhood of Baba Amr which has been devastated by a month of shelling by government forces.
"We are demanding unfettered access for the humanitarian agencies who are there on the ground. We continue to push in every way we possibly can for this unfettered access," he said.
He indicated Britain would oppose any moves by countries in the region to supply arms to the Syrian rebels, as they demanded at Friday's meeting in Tunis of the international Friends of Syria group.
"We need to stop the fighting, not boost it in any way at all," he said.
He warned, however, that the regime would be held to account for its actions.
"This is an evil regime that has turned its guns on its own people. It is despicable what's happening and we will hold them to account in every way that we can for the human rights abuses that are going on," he said.