US Secretary of State Hillary Clinton called for the world community to target Syrian oil and gas exports and again urged Mr Assad to step aside.

EU ministers meet in Poland on Friday to discuss sweeping new sanctions.

In Syria, activists are preparing another day of protests, under the slogan "death rather than humiliation".

They said that on Thursday another seven people were killed by security forces.

The United Nations says more than 2,200 people have been killed in six months of protests.