Two Americans shot in Saudi Arabia are employees of defence contractor Vinnell Arabia

RIYADH (AFP) - Two Americans who came under fire in Saudi Arabia this weekend are employees of a US defence contractor, the firm said on Sunday, confirming the second attack in recent months against Vinnell Arabia.

"We can confirm that two Vinnell Arabia employees were involved in an incident on Friday, in which they were shot at by assailants in the al-Ahsa province of Saudi Arabia," the company said in a statement issued through a public relations firm.

"Both employees were injured but are in stable condition at a local hospital," it added.

Saudi police said earlier that one American had been wounded in a shooting.

"A car carrying two American nationals... came under fire from an unknown source," on Friday afternoon in al-Ahsa, in Eastern Province, source of most of the kingdom's oil wealth, police said.

Vinnell Arabia provides training for the Saudi Arabian National Guard, a parallel army.

The attack is the fourth against Westerners in the kingdom since October. It comes as Saudi Arabia participates in US-led air strikes against the Islamic State in Iraq and Syria (ISIS) group in Syria, raising concerns about possible retaliation inside the kingdom.

In October, one Vinnell employee was shot dead and another wounded at a petrol garage in the capital Riyadh.

The interior ministry identified the suspected shooter as Abdulaziz Fahad Abdulaziz Alrashid, 24, a US-born Saudi who had been fired from Vinnell Arabia.

The ministry said at the time that the suspect, who was shot and wounded in a gunfight with security forces, had no "prior links" with extremist groups.