Fierce clashes erupted on two fronts in the Yemeni capital, Sana'a, on Saturday, a day after the U.N. Security Council passed a resolution condemning the government's crackdown on dissent.

Witnesses say security forces have raided neighborhoods that are home to family members of an opposition tribal leader, Sheik Sadeq al-Ahmar. They say plumes of smoke have been seen rising from several areas.

In another part of Sana'a, government forces have clashed with loyalists of Ali Mohsen al-Ahmar, a Yemeni general who joined the opposition.

Friday's Security Council measure was the body's first resolution on Yemen since widespread protests against President Ali Abdullah Saleh began earlier this year.

It calls Yemen's use of force against protestors excessive and says “those responsible for violence, human rights violations and abuses should be held accountable.”

The resolution also reaffirms support for a Gulf Cooperation Council initiative that calls for Mr. Saleh to transfer power to a deputy in exchange for immunity from prosecution.

Mr. Saleh has agreed to the plan several times, but each time, he has backed away without signing the deal.

For the past ten months, opposition activists have been demanding an end to Mr. Saleh's 33-year autocratic rule. Dozens of people have died in protest-related unrest over the past few days.

Yemen has also been plagued by violence linked to al-Qaida militants.