The International Committee of the Red Cross (ICRC) and the Syrian Arab Red Crescent have said the situation in several parts of Syria has "worsened". The ICRC said in a statement:
The situation in several parts of Syria is deteriorating sharply. We understand that hundreds of people have left several combat-affected areas and headed to safer ones within Homs governorate.
The ICRC cannot confirm the reports of civilians being used as human shields. If this is confirmed, it is completely unacceptable.
The United States and Russia are embroiled in a furious diplomatic row after both sides accused each other of supplying arms to Syria.
The US Secretary of State has accused Russia of escalating the conflict in Syria and lying about their involvement in the country.
Foreign Secretary William Hague has told MPs in the House of Commons that Syria is "on the edge of civil war."