A disabled sheikh has turned himself in to the Saudi authorities under a government amnesty for militants.
Saudi Arabia is on high alert for more militant attacks
Khaled al-Harbi aka Abu Suleiman al-Makki surrendered in Tehran after spending years on Iran's Afghan border.
According to some reports the paralysed sheikh had appeared in one of Osama Bin Laden's video tapes praising the 11 September attacks in the US.
His surrender comes after a senior Saudi expressed dismay that very few militants had applied for the amnesty.
Mr Harbi was seen in Saudi televised footage being carried off a plane in a wheelchair after arriving in the kingdom from Tehran.
His name does not appear on the list of the kingdom's 26 most wanted militants and it has not been announced what he is wanted for.
The December 2001 videotape - thought to have been filmed in the Afghan city of Kandahar - was taken by the Bush administration as proof that Bin Laden
masterminded the 11 September attacks.
Saudi diplomats arranged travel documents for Mr Harbi after he turned himself in at the Saudi embassy in Tehran, the interior ministry said.
"Thank God, Thank God... I called the embassy and we were very well received," he told Saudi TV at the airport terminal. "I have come obeying God, and obeying the rulers."
He described the amnesty as "generous" and urged others to take advantage of it.
He was accompanied by an unidentified woman dressed in black and a teenage boy.
After arriving back in Saudi Arabia, Mr Harbi was taken to hospital for
medical treatment, officials said.
Past reports have identified him as Bin Laden's interlocutor in the Kandahar videotape, saying he was married to the daughter of al-Qaeda's number two, Ayman al-Zawahri.
On Monday, Interior Minister Prince Nayef Bin Abdul Aziz expressed disappointment that the amnesty appeared to have been largely ignored by militants who have shattered Saudi security in the last 14 months.
About 90 people have died in a wave of attacks since May 2003 that have been blamed on al-Qaeda supporters.
Only two others militants have availed themselves of the amnesty offer announced on 23 June.
But Prince Nayef said the one-month deadline for the amnesty would not be changed and he said hundreds of people had been taken into custody and some had already been tried and convicted.