A document purporting to be an official U.S. government news release and suggesting that Egyptian President Anwar Sadat should be outsted has been published by a leftist magazine here. The U.S. embassy has denounced the document as a forgery.

The evidence that the document is a fake is persuasive. But if it is a forgery, it is cleverly done. The purported press release had reportedly been arousing some concern in governmental and intellectual circles where it circulated from some time before it was actually published. A Statement issued by the embassy calls it "an attempt to poison U.S. - Egyptian relations."

Predictably, the embassy's repudiation of the document has given it greater circulation and attention than it would otherwise have had. The embassy statement, distributed in English and Arabic, was disseminated around the Arab world by the official Middle East News Agency and printed this morning by the three major daily newspapers in Cairo.

That brought it to the attention of thousands of readers who did not see it in the magazine Rose A Youssef, a leftish weekly with an estimated circulation of 35,000.

The document, in English, was written on letterhead stationery of the U.S. Information Service office in Athens. According to the embassy here, it was distributed by mail from Athens.

It purports to be an account of a speech said to have been given to the Detroit Economic Club on March 24, 1976, by Edwin Yeo, former under secretary for monetary affairs of the Treasury.

It quotes Yeo as saying the Egyptian economy was "suffering from a deep crisis and is in such a deplorable state that no economic or financial injection can avert its disintegration and bankruptcy."

It also quotes him as saying that the "present Egyptian leadership" is incapable of dealing with this crisis. Yeo is quoted as telling a questioner after the speech that he agreed with the proposition that American businessmen will not invest in Egypt unless they have assurances that their capital will be protected against seizure or nationalization, by U.S. military intervention if necessary.

According to the putative press release, Yeo delivered these remarks after accompanying former Treasury Secretary William Simon on a tour of the Middle East a year ago.

The statement issued by the U.S. embassy here in reponse to the publication of the document says that Yeo did not come with Simon on his tour, has in fact never been to Egypt, "has never spoken before the Detroit Economic Club on any subject," and was in Washington, not Detroit, on the date in question.

The U.S. Information Service in Athens "did not issue this document," the U.S. statement says.

An embassy spokesman said that no one from Rose Al Youssef had contacted the embassy here to check on the authenticity of the document before printing it.

That magazine has often been critical of Sadat's economic policies and of Egypt's turn away from its ties with the Soviet Union in favor of an economic opening to the West.