Members of the United Nations Security Council are meeting Friday to consider a resolution on the future of the U.N. observer mission in Syria.

The meeting in New York follows Thursday's Russian and Chinese veto of a resolution that would have extended the mission's mandate past its expiration Friday at midnight. It is the third resolution vetoed by Russia and China, who have also voted against imposing sanctions against Syria, unless authorities halt the violence.

Earlier, Syrian state television reported the country's national security chief died from wounds suffered in a rebel blast in Damascus on Wednesday.

General Hisham Ikhtiyar is the fourth high-level Syrian official to die as a result of the bombing in Damascus, the scene this week of fierce clashes between government troops and rebel forces. The London-based Syrian Observatory for Human Rights said more than 300 people were killed Thursday, in what is believed to be the deadliest day in the 16-month uprising against President Bashar al-Assad.