Syrian state television says a suicide bomber has struck the National Security building in Damascus, killing defense minister Daoud Rajha and seriously wounding several other officials.

The attack Wednesday comes amid days of clashes between rebels and government troops in the capital.

Meanwhile, the United Nations Security Council is expected to vote Wednesday on a resolution that would extend the U.N. observer mission in Syria.

The mission's mandate expires Friday and the Council has been divided about whether a new resolution should include a threat of sanctions against President Bashar al-Assad's government.

Britain, France, the United States and Germany have proposed a draft calling for sanctions, if Syria does not implement U.N. envoy Kofi Annan's peace plan. Russia has promised to veto that version. Russia's draft does not include any sanctions.