Syrian activists say rebel forces battling for control of the northern city of Aleppo are engaged in heavy fighting with pro-government forces.

Friday's clashes were described by residents and activists as unprecedented, and come as part of a new rebel offensive to push regime forces out of the city.

Elsewhere in the country, the Britain-based Syrian Observatory for Human Rights reported clashes in Deir Ezzor, Dera'a, Hama, and in the capital, Damascus.

Meanwhile Friday, ministers from several Western nations and their allies will gather to discuss coordination efforts among Syria's fractured opposition.

Friday's ad-hoc meeting of selected members of the Friends of Syria group, is hosted in New York by U.S. Secretary of State Hillary Clinton and will include ministers from more than 20 nations and representatives from local revolutionary councils.

A senior State Department official said the meeting, which takes place on the sidelines of the U.N. General Assembly, will focus on support to the Syrian opposition, humanitarian assistance and international pressure on the Syrian regime.

The official says the discussions will include unilateral measures which can be taken against the regime including the possibility of sanctions.