The Saudi government and the Arabian American Oil Co. have completed negotiations on a complete government takeover of Aramco, the world's largest oil-exporting enterprise, the Saudi state oil company's governor was quoted as saying today.

But an Aramco spokesman in New York said the company has not been advised of any new developments in the pending takeover. "Negotiations haven't been concluded," he asserted.

Abdul Hadi Taher, chief executive of Petromin, the Saudi state firm, told the weekly magazine Saud Business that "Practically speaking, the agreements are being implemented."

Taher said the deal still awaits final signatures by "higher government authorities," presumably King Khalid. He declined to reveal details of the reported accord under negotiations for more than two years, or say what was holding up the signatures.

The Saudi government already owns 60 per cent of Aramco, which produces all but a fraction of the Saudi output of 8.5 million barrels a day in 1976. The remaining 40 per cent belongs to Standard Oil Co. of California, Exxon Corp., Texaco, Inc., and Mobil Corp.

The Saudi oil minister, Sheik Ahmed Zaki Yamani, has said the Aramco takeover will be retroactive to Jan. 1, 1976. As of that time, Aramco's book value stood at about $2 billion.