UN Secretary-general Ban Ki- moon on Wednesday strongly condemned a bomb attack at the National Security Headquarters in the Syrian capital Damascus, calling for the cessation of all violence in all forms.

In a statement released by his spokesperson, Ban reiterated that acts of violence committed by any party are " unacceptable," and are a clear violation of UN-Arab League Joint Envoy for Syria Kofi Annan's six-point peace plan.

Ban is also gravely concerned about reports of the continued use of heavy weapons by the Syrian security forces, including in the Damascus area, against civilians, despite repeated government assurances that such weapons would be withdrawn, said the statement.

"The deteriorating situation in Syria underscores the extreme urgency for all sides to stop armed violence in all its forms, implement the six-point plan and move swiftly towards a political dialogue and a peaceful, democratic Syrian-led transition," Ban noted.

Syrian Defense Minister Daoud Rajha was killed and some other senior officials wounded on Wednesday in a suicide bombing that tore through the National Intelligence compound in Damascus, state TV reported.

The blast occurred when several ministers and intelligence chiefs were having a meeting in the targeted building.

The Syrian Ministry of Defense has vowed to eradicate armed rebel groups and their hideouts.

Also in the statement, Ban urged the UN Security Council to shoulder its responsibility and take collective and effective action on the basis of UN Charter obligations and in view of the seriousness of the situation on the ground.

"Time is of the essence. The Syrian people have suffered for too long. The bloodshed must end now," Ban stressed.