UN humanitarian chief Valerie Amos calls for unlimited aid access to Syria's worst hit areas.
Speaking at a news conference in Ankara, Amos said she had spoken to Syrian government representatives but they'd asked for more time.
SOUNDBITE) (English) U.N. HUMANITARIAN CHIEF, VALERIE AMOS, SAYING:
"However,the government have agreed to a limited assessment exercise to be conducted by U.N. agencies and the Syrian authorities, which would give us some information about what is happening in the country."
Meanwhile, amateur videos from Syria posted on to a social media website - which Reuters cannot independently verify - purportedly reveal fresh fighting amid reports that 31 people were killed.
This burning car is reportedly in the Asheera neighbourhood of Homs while this amateur Homs footage shows smoke billowing from buildings amid sounds of heavy gunfire.
This footage, apparently from Damascus, purports to show a group of protesters chanting anti-regime slogans outside the captal's Russian embassy.
The resumption of the heavy shelling follows a few days of relative calm during which Amos visited Homs and said part of the city had been completely destroyed.
UN and Arab League evnoy Kofi Annan is due to arrive in Damascus on Saturday to try to calm the year-old conflict.
Sunita Rappai, Reuters