Mr Assad was shunned by many fellow leaders after his government's violent crackdown on pro-democracy protests triggered a civil war in which half a million people have been killed.

Syria was readmitted this month after states which had backed the opposition accepted his grip on power was secure.

They include summit hosts Saudi Arabia.

The rapprochement accelerated following the devastating earthquake that hit Turkey and north-western Syria in February, when once-hostile powers decided to send humanitarian aid to Syrian government-controlled areas.

China also brokered a surprise agreement in March that saw Saudi Arabia restore diplomatic ties with its long-time regional rival Iran, which along with Russia has helped Mr Assad's forces regain control of Syria's biggest cities.

Large parts of the country are nevertheless still held by Turkish-backed rebels, jihadists, and Kurdish-led militia fighters supported by the United States.

Half of Syria's pre-war population of 22 million have had to flee their homes. Some 6.8 million people are internally displaced, while another 6 million are refugees or asylum-seekers abroad.

Even before the earthquake struck an estimated 15.3 million people inside Syria were in need of some form of humanitarian assistance - an all-time high since the war began.

President Assad arrived on Thursday night in the Red Sea port city of Jeddah, where this year's Arab League summit is taking place.

At a meeting of the foreign ministers of the 22 member states on Wednesday, Arab League Secretary General Ahmed Aboul Gheit declared that he hoped that "Syria's regaining of its seat is a precursor to the end of its conflict".

Saudi Foreign Minister Prince Faisal bin Farhan Al Saud also welcomed Syria.

"Our world today is facing numerous challenges and difficulties that place us at a crossroads," he said. "It is necessary for us to stand together and try harder to strengthen joint Arab action to meet them."

But not every country was enthusiastic about Syria's reinstatement.

Qatar's foreign minister told a news conference in Doha that it had dropped its opposition only because it did not want to "deviate from the Arab consensus".

The US meanwhile said it did "not believe that Syria merits readmission".

"Our position is clear - we are not going to normalise relations with the Assad regime, and we certainly don't support others doing that as well," state department spokesman Vedant Patel told reporters.