HAFAR AL-BATIN, SAUDI ARABIA, AUG. 25 -- Thousands of Arab troops from other nations, providing political legitimacy to the American buildup here, have begun digging in across the northern Saudi desert alongside Saudi forces to help defend the kingdom from possible Iraqi attack.

Western reporters were allowed for the first time today to visit Egyptian and Moroccan special forces units at several locations north of here, toward the Saudi-Iraqi border where the Saudi-led, six-nation Gulf Cooperation Council has spread out two mechanized brigades in defense of the kingdom.

"They are getting ready to deal with any change in the military situation," said a Saudi colonel, who added that the Saudi army also had brought in an armored brigade to reinforce defenses here at this strategic crossroads, close to where the borders of Kuwait, Iraq and Saudi Arabia come together.

Egypt and Syria each have sent elite special forces commandos, and Morocco a small detachment from a motorized brigade that has been fighting a desert war in the Western Sahara for over a decade. While their numbers are small -- 2,000 or fewer -- the quality of the units is said to be excellent. Above all, the decision of these Arab nations, particularly Syria, to send forces here has made it much easier for Saudi Arabia to defend its decision to invite tens of thousands of American troops into the country where two of Islam's holiest sites, Mecca and Medina, are located.

Baghdad radio continues to broadcast erroneous reports that U.S. troops are stationed in Saudi Arabia's western Hijaz province, protecting Islam's holy places. The broadcasts are a propaganda ploy to discredit the Saudi government in the eyes of Moslems.

The Egyptian colonel commanding the 2,000-man special forces contingents said he had no qualms about possibly becoming involved in a war against Moslem Iraq, even though Egypt had provided arms, thousands of army volunteers and technical expertise to the Iraqis during their eight-year war with Iran. That war ended in a cease-fire in 1988.

"I am defending the Saudi Arabian territory, regardless of who the offender is, because it is holy land so far as Moslems are concerned," said Col. Abdel Rahim Mohamed Said.

He also justified Egypt's military aid to Saudi Arabia by quoting an Islamic proverb that says if a person breaks a treaty or agreement, "it is the duty of all the other Moslems to get together and bring that person to justice."

The Egyptian special forces arrived here only eight days ago and the Moroccans four days ago. It was not clear when the Syrian forces had come. They refused to allow Western reporters to visit their camp today.

Even with Saudi tank reinforcements, the Arab multinational force taking shape here seems very small and lightly armed compared to the more than 170,000 Iraqi troops and 1,000 tanks and armored vehicles now assembled in occupied Kuwait. The desert here seems perfect for tanks, with a packed surface and no sand dunes to get in the way.

There were no signs of any American troops here today, and Saudi officials said they did not know if any would be stationed in the desert here or at the sprawling King Khalid Military City 35 miles south of Hafar al-Batin, the base for the Gulf Cooperation Council's "Peninsula Shield" force.

According to Arab sources, the only American presence anywhere along the Iraqi border is at Arar, about 300 miles west of here, toward the Jordanian border where there is a U.S.-manned radar site and some Special Forces commandos.

The Iraqis so far have not engaged in any serious buildup of troops along the Saudi-Iraqi border, according to Maj. Gen. Turki Hodijan, the Gulf Council's commander of a 4,500-man brigade.

He told visiting reporters that Iraqi troops, as well as the multinational forces, were roughly 25 miles from the border. He said no unusual Iraqi troop movements have been noticed so far in his sector.

Saudi officers seemed eager today to show that their own troops are well prepared for a possible conflict with Iraq and that they are being extremely well looked after in the barren desert conditions here.