A Turkish journalist working for United Press International in Ankara says that he has been threatened and beaten by Turkish government police and that the government has not honored five months of promises to issue him a passport.

The Turkish Embassy says the journalist, Ismet Imset, has been charged with links to antigovernment organizations. An embassy official said yesterday that a trial on those charges has gotten under way.

Imset, 24, said in a telephone interview from Ankara that he applied for the passport in March in order to attend a UPI training course in London. He said he was told that it would be granted. Pursuing the effort March 16 in an Istanbul police station, he was blindfolded for three hours, beaten and released, he said. His papers were subsequently delivered stamped to indicate that he was banned from travel abroad.

Since then, he said, he has repeatedly been told that the action will be rescinded and a passport will be granted. Last week, he said, government officials telephoned his office to warn him not to print a story about Nigerian students who were demonstrating at the Nigerian embassy in Ankara.

"I was warned that the story should not be carried in the domestic press, and they told my assistant, 'After this we regard him as being warned,' " Imset related.

He said the Nigerian story had little importance in Turkey, "but if I had listened, they would then warn me on other political stories. It's all a part of an intimidation operation." Turkish media are routinely subject to censorship, and journalists have frequently been jailed.

UPI complained of the beating incident to the Turkish government and informed the U.S. Embassy in Ankara. Rep. Stephen Solarz (D-N.Y.) received a letter dated April 13 from Turkey's ambassador to the United States, Sukru Elekdag, promising that Imset "will be granted a passport to travel abroad," and noting that police denied that there had been any beating.

"Mr. Imset can sue the people he claims have acted in such an illegal fashion," the letter said.

State Department officials here said they understood Imset was barred from travel because a 1978 charge of weapons possession is still pending against him. Neither UPI nor Imset has asked for U.S. help in the matter, the officials said.

A Turkish Embassy spokesman confirmed yesterday that Ismet was being tried on charges of having ties to organizations trying to violently overthrow the government. The spokesman said he had no details on the case.

UPI foreign editor Paul Varian said in New York that he was not aware of any legal restrictions against Imset's departure. Turkish law permits those awaiting court verdicts to travel if no court has ruled otherwise, and Imset said there is no court ruling against him.

"He's been given the runaround and beaten up, and we are trying to get him out of the country," Varian said. Two UPI executives went to Turkey and repeatedly were assured by Turkish officials that a passport would soon be granted, he said.