The International Committee of the Red Cross (ICRC) said on Wednesday it was trying to evacuate civilians stranded in and around Homs amid fighting in the central Syrian city.
"Our first priority, together with the Syrian Arab Red Crescent, is to evacuate the wounded and the sick to safer areas, where they can be treated," said Beatrice Megevand-Roggo, ICRC's head of operations for the Near and Middle East.
The humanitarian agency said it made a request for a temporary halt in fighting on Tuesday to government and opposition groups. Both parties said they would respect the pause.
"The ICRC and the Syrian Arab Red Crescent are ready to enter the old city of Homs and the neighbourhoods of Al-Qarabees, Al-Qusour, Jurat al-Shayyah and Al-Khalidiya," Megevand-Roggo said.
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"We also want to evacuate civilians who have been unable to flee the conflict area, and bring in much-needed aid and medical supplies to the local Syrian Arab Red Crescent branch."
Troops loyal to the regime of President Bashar al-Assad have been bombarding parts of the city for days with a view to retaking the rebel stronghold.
Hundreds of people are believed to be trapped in the old city and are unable to flee or find shelter because of the fighting, the Geneva-based agency said.
The Red Cross action follows a statement by the UN's peacekeeping chief Herve Lasdous that UN observers will stay in the country despite the risks.
The 300-strong mission was suspended after it came under attack.
Monitors estimate that 15 months of fighting have claimed the lives of more than 14,400 people, the majority of them civilians.