Two master practitioners of the art of espionage have faced each other across a liaison table in Saudi Arabia for the past six years. Now, the American spy has moved across the table and is working for Saudi Arabia's intelligence chief.

"It is an unusual situation, but the CIA does not seem to be bothered by it and I don't think our embassy is either," said one Carter administration official who has watched the movement by Raymond H. Close, the recently retired Central Intelligence Agency station chief in Saudi Arabia, into a job as a paid adviser to Saudi intelligence chief Kamal Adham.

The lack of objection is another indication of the close liaison the Saudi and U. S. intelligence operations maintains, American officials acknowledge. Close has worked quitely out a housing compound across the street from a key Saudi ministry in Riyadh for the past six years.

It is not clear if he is going to work for Adham's intelligence apparatus, his expanding business interests, or both.

Brother-in-law to the late King Faisal, the Turkish-born Adham has headed the Saudi internal and foreign intelligence operations for two decades. Now, the Saudi equivalent of the FBI has been turned over to another member of the royal family, while Adham concentrates on upgrading the CIA-type network.

But Adham has also set up private companies to net a share of the lucrative commissions that have been cascading on Saudi agents in arms and civilian capital goods deals. He has been especially active in business since the death of Faisal, for whom Adham evidently acted as a business manager as well.