Six months ago Arkday Shevchenko was proclaimed to be a Soviet spy who came in from the cold, quitting his $87,000-a-year United Nations post to seek refuge in the United States.

Two months later he was touring the sunny Carribbean with a female escort, paying her $5,000 a month for her companionship with CIA funds, she claimed on national television last night.

Judy Chavez, the American escort, said in an NBC television interview yesterday that she plans to write a book about her fling with the former Soviet diplomat. Shevchenko purchased a $9,000 sport cars for her and then, in June,took her to a resort in the Virgin Islands on a holiday, she said.

Shevchenko's high living so concerned the Central Intelligence Agency that she said at one point FBI agents called her and requested "an emergency meeting" to determine exactly how much cash the former Soviet diplomat was passing on to her. She estimated that she had received between $35,000 and $40,000.

"What they told me," she said, "was that Arkady goes to a high official in the CIA. He, in turn, gives the money to Arkady who in turn gave the money to me."

After Chavez' revelation was aired yesterday a CIA spokesman acknowledged that the intelligence agency was indeed giving Shevchenko a regular stipened "to help him along until he becomes established in his own identity." The spokesman said the arrangement was "pretty standard" for defectors, but he declined to say how much Schevchenko was paid.

Shevchenko, asked during an interview about the woman's claim, declined to comment. The network said it attempted to interview the former diplomat at a restaurant here while he was accompanied by a CIA official.

According to CHavez, the former Soviet diplomat maintained a checking account of about $50,000 in a bank here. Shevchenko's former attorney, Ernest A. Gross, said last night that Shevchenko settled with the United Nations for $78,000 when he left his post under secretary general. Schevchenko moved to the District of Columbia in May, said Gross.

Chavez said that Schevchenko gave her $500 a night after she met him through an escort service. As the arrangement became more regular she said he padi her $5,000 every month."

The 47-year-old former U.N. official is the highest-ranking defector ever to leave the Soviets. When he announced through his attorney that he would not go home Soviet officials attempted to claim that he was being held in the United States "under duress." The charge was denied by Gross at the time as "ludicrous."

Gross said yesterday that Shevchenko, whose assumed name was not disclosed by NBC, had received several offers of jobs from universities and that several publishers also were seeking to have him write a book.