BEIRUT-- A key Syrian opposition group is calling for international protection for civilians ahead of an expected visit to Damascus by senior Arab officials.

The delegation led by the prime minister of Qatar is expected to arrive in Syria Wednesday to discuss the possibility of starting a national dialogue between the opposition and President Bashar Assad's regime.

But a statement issued Tuesday by the Syrian National Council makes clear there can be no dialogue with the government while it continues to the military crackdown on protesters that the U.N. says has already killed 3,000 people.

The statement called for Arab and international observers to be allowed into Syria immediately. It did not elaborate.

Syria has grown increasingly isolated during the crisis. The U.S. pulled out its ambassador to Damascus Monday.