Damascus: Security forces killed at least five people in Syria, activists said, urging fresh anti-regime protests under the banner of "death rather than humiliation."

A senior official, meanwhile, said in a contested video that he has resigned in disgust at hundreds of killings and thousands of arrests by President Bashar al-Assad's regime.

The Syrian Observatory for Human Rights said three people were killed and several more were wounded when security forces opened fire on protesters in the central region of Homs.

According to the Local Coordination Committees (LCC), which group activists on the ground, armoured cars entered the city of Homs itself.

The Britain-based Observatory also reported "one dead and five wounded in an assault by the army and security forces on the village of Al-Rama" in the northwestern province of Idlib, near the Turkish border.

And the LCC said a young man was killed by pro-regime militiamen in the eastern city of Deir Ezzor.

A girl of 10 was also reported to have died of wounds suffered late on Wednesday during a shooting near police headquarters at Deir Ezzor in eastern Syria as she rode in a taxi with her family.

The security forces went into action on Thursday after mass demonstrations late on Wednesday in several districts of Homs, the Observatory said.

The United Nations says that more than 2,200 people have been killed since the beginning of near-daily protests across the country against Assad's regime in mid-March.

The head of the Syrian League for the Defence of Human Rights, Abdel Karim Rihawi, said dozens of people had been arrested on Wednesday at Qadam and Qabun in the Damascus region, and at Zabadani, northwest of the capital.

Activists on their Facebook page Syrian Revolution 2011 defiantly called for fresh protests on Friday, the Muslim weekly day of prayers and rallying point for demonstrations.

The rallies will be held under the slogan of "death rather than humiliation," it said. "We are ready to die in the millions as martyrs."

The LCC said demonstrations would continue "every day until the downfall of the regime."