Syrian authorities have blocked an aid convoy carrying emergency supplies from entering the Baba Amr district in the city of Homs, the International Committee of the Red Cross says.
The president of the Red Cross says the decision to deny aid groups access to Baba Amr is "unacceptable".
Jakoba Kellenberger said the aid group would stay in Homs overnight in the hope of entering Baba Amr "in the very near future".
The Syrian government had given the Red Cross permission on Thursday to enter Baba Amr after security forces took the district from rebels.
"It is unacceptable that people who have been in need of emergency assistance for weeks have still not received any help," said Kellenberger.
"We are staying in Homs tonight in the hope of entering Baba Amr in the very near future," he said in a statement.
Meanwhile, the group and its Syrian sister organisation would help those families that have fled Baba Amr, Kellenberger said.
The Red Cross is also still waiting for the Syrian government to agree to its call for a daily two-hour ceasefire to allow it to bring humanitarian aid into areas where fighting is taking place, and to evacuate the wounded.
The group made its call for a ceasefire more than a week ago.
"The humanitarian situation was very serious then, and it is worse now," said Kellenberger.
The bodies of two journalists killed in Syria, Sunday Times reporter Marie Colvin and French photographer Remi Ochlik, have been handed over to the International Committee of the Red Cross by the Syrian authorities and are being taken to Damascus, a spokesman for the charity said today.