There was no word either from Saudi authorities or US diplomats on whether security forces were nearer to locating Paul Johnson despite intensive overnight searches of several Riyadh neighborhoods that went on until the early hours.

After Johnson's son went on US television to urge the Saudi government to strike a last-minute deal with the captors, his Thai wife appeared on a Saudi-owned Arab satellite TV to plead tearfully for her husband's release.

But the most remarkable intervention came from a senior Saudi cleric and official who chose a rostrum revered by more than a billion Muslims worldwide to deliver an emotional plea for an end to attacks on non-Muslims in Saudi Arabia.

"Listen to the words of sheikh al-Islam demanding the release of captives: 'We cannot accept anything other than the release of all Jewish and Christian captives. They are under our protection'," Sheikh Saleh bin Abdullah bin Humaid told worshippers at the Great Mosque in Mecca, Islam's holiest shrine.

Sheikh al-Islam – a reference to famous Islamic scholar Ahmad bin Abdul Salam al-Taymiyah, known as Ibn Taymiyah – said this "despite the fact that he was at war with the Crusaders," bin Humaid said, his voice breaking at several points as he denounced violence against Muslim and non-Muslim alike.

Bin Humaid, who is also speaker of the appointed Shura (Consultative) Council, referred repeatedly to non-Muslims here as being under the protection of their Saudi hosts.

"In Islam, it is not permissible to harm them or attack them – neither in terms of their lives nor properties ... Even when it comes to argument, we Muslims were ordered to use the gentlest ways," Bin Humaid said.

"Their rights are upheld in Islam and in Muslim lands – their souls are sacred, on a par with Muslims," he said, echoing remarks by Crown Prince Abdullah on Tuesday that all Saudis had a duty to protect expatriates.

Both Saudi Arabia and the United States have ruled out negotiations with terrorists, but Saudi newspapers carried a reminder Friday that Riyadh had not long ago chosen to save captives' lives and level the score with captors later.

Papers front-paged remarks by the interior minister to a French daily, published Thursday, in which he virtually confirmed that three of four gunmen who killed 22 people in a shooting and hostage-taking rampage in the eastern oil city of Al-Khobar last month were allowed to escape.

Saudi authorities "chose to save lives" and arrest the terrorists later, Prince Nayef bin Abdul Aziz told Le Figaro.

"This does not mean that we did not want to arrest the terrorists. I am sure our (security) services will find them," Nayef said.

An Al-Qaeda affiliate calling itself "Al-Qaeda in the Arabian peninsula" posted a video on a website Tuesday showing Johnson and giving the Saudi government a 72-hour ultimatum to release detained members or sympathizers of the terror network, estimated to number more than 700.

The group has claimed responsibility for other fatal attacks against Westerners in the oil-rich kingdom, leaving little doubt that it was prepared to carry out its threat to execute the 49-year-old captive.

The aeronautics engineer with top US defense contractor Lockheed Martin was working, apparently on a contract basis, with a Saudi electronics firm, according to telephone numbers appearing in the video.

Asked whether he favored the militants being released, Johnson's son, Paul Marshall Johnson III, told NBC television Thursday: "Yes, I would. I don't want to comment on it; I just want my father home.

"I just really think the Saudi government will do whatever it takes for my father's safe return home," he said.

In Riyadh, Johnson's wife Thanom was in tears as she pleaded for his release on Dubai-based Al-Arabiya news channel Friday.

"I want him to come back to me... He didn't do anything wrong," she said.

A Saudi colleague of Johnson posted a message on Al-Arabiya's website calling for his release on the basis of a traditional Muslim tribal form of protection.

If Johnson's kidnappers, who have been holding him since he was abducted in Riyadh on Saturday, are good Muslims, "they will free him after hearing this message," Saad al-Momen wrote.

"I offered 'ijara' to this man," Momen said, in reference to the traditional offering of security and protection.

Saudi security forces combed districts in southern and northern sectors of the capital for two consecutive nights Wednesday and Thursday, raiding houses and confiscating computers and CDs.

But there was no word of arrests and no information on whether the raids had brought them closer to establishing Johnson's whereabouts.

The United States, revising an existing April 15 alert, on Thursday renewed a warning for US citizens not to travel to Saudi Arabia and for those in the kingdom to leave immediately due to terror threats.AFP