* Sudanese general to head observers, in Cairo for briefing
* Arab observers will demand free access across Syria
* Syria had balked over accepting observers for six weeks (Adds team arrives in Damascus)
CAIRO, Dec 22 (Reuters) - An advance team from the Arab League arrived in Syria on Thursday ahead of deploying monitors who will assess whether Damascus is acting to end a bloody nine-month crackdown on protests against President Bashar al-Assad's rule, a League official said.
"We arrived in Damascus safely," Waguih Hanafy, a senior aide to Arab League chief Nabil Elaraby and who is travelling with the team, said by telephone from the Syrian capital.
In Cairo, Sudanese General Mohammed Ahmed Mustafa al-Dabi arrived for talks at the League headquarters to be briefed on his role in leading the 150-strong observer team that could be sent to Syria before the end of December, provided preparations go smoothly.
Syria agreed in November to an Arab plan demanding an end to fighting, the withdrawal of troops from residential areas, the release of prisoners and the start of a dialogue with the opposition. It balked for six weeks over letting in monitors.
In that time, the League imposed economic sanctions and threatened to escalate the matter to the U.N. Security Council, while the death toll has soared as Syria has turned its troops and tanks against demonstrators.
It finally signed a protocol on monitors on Monday.
Dabi, who coordinated between Sudan's government and international peacekeepers there, told reporters at Cairo airport he would meet League Secretary-General Nabil Elaraby to follow up on arrangements for the observer mission.
He said observers would work "with complete transparency to observe the situation in Syria", adding it would hold continuous meetings in the field with all factions, including the Syrian army, opposition, security forces and humanitarian groups.
League Secretary-General Nabil Elaraby told Reuters on Tuesday that 150-strong observers would demand free access to hospitals, prisons and other sites across the country.
He also said the team would issue daily reports that would be shown to but not vetted by the Syrian authorities. Elaraby said the monitors could be in Syria before the end of December.
The advance team making preparations for the mission is led by top League official Samir Seif al-Yazal and comprises 11 people, including financial, administrative and legal experts, officials said.
"During our visit to Syria, we will work on some necessary arrangements to receive the mission on the ground, such as accommodation, transport, communications and security," Yazal said shortly before he flew out of Cairo.
Elaraby said monitors would need no more than a week from arrival to see whether Syria was abiding by the peace plan. He said 10 four-wheel drive vehicles were being sent from Iraq to Syria to help out the observers. (Writing by Edmund Blair)