BEIRUT, Lebanon (AP) _ An underground group today claimed it kidnapped a 55-year-old American and alleged he worked for the CIA and the Israeli secret service. The United States denied the charges.

The Revolutionary Justice Organization, a group believed made up of Shiite Moslems loyal to Iran, identified the hostage as Edward Austin Tracy of Vermont.

If Tracy's abduction is confirmed, he would be the seventh American missing in Lebanon. The Revolutionary Justice Organization claims to hold one of the previous American kidnap victims.

The group made its claim in a handwritten note in Arabic delivered to the Beirut office of a Western news agency. The statement was accompanied by a photograph of Tracy and a photocopy of his passport.

The white-haired Tracy writes illustrated children's books. He was one of the fewer than a dozen Americans who remained in west Beirut after the latest exodus of foreigners in April prompted by a series of politically motivated kidnappings.

Tracy's mother, Doris, 78, said in a telephone interview from South Burlington, Vt., that her son has ''been gone from Burlington for more than 20 years, and I didn't hear from him for about 10 years, but then he began writing to me about a year ago.''

She said she is worried about her son being in Beirut, ''and the fact that I don't know what he's doing. He never says what he's doing.''

The underground group did not say when or where Tracy was abducted.

''The Revolutionary Justice Organization announces the arrest of Jewish American spy called Edward Austin Tracy after he was definitely proven to be ... feeding the (Israeli secret service) Mossad and the CIA with information (and) ... spying for the CIA,'' the group said in its statement.

In Washington, White House spokesman Larry Speakes said Tracy ''has no connection with the U.S. government. Allegations of his kidnappers that he works for the CIA are totally without foundation.''

In Tel Aviv, officials in the Foreign Ministry and the office of the prime minister declined comment on the allegations Tracy was linked to Mossad.

A U.S. Embassy official said Tracy had been living in west Beirut for a long time. The official said he could not confirm that Tracy was kidnapped.

''But we have not heard of him lately. This guy had not had any contact with the embassy in recent months,'' said the official, who spoke on condition of anonymity.

Tracy often was seen sitting in sidewalk cafes in west Beirut's Hamra commercial thoroughfare. Lebanese waiters who know him said they have not seen him in two months.

He speaks some Arabic and frequently visited U.S. news agency offices in Beirut to seek help in marketing his books. Sometimes he carried copies of the Bible and the Koran which he said were for sale.

He was said to be a friend of Yasser Arafat before the Palestine Liberation Organization chairman was ousted from Beirut in Israel's 1982 invasion.

Tracy graduated from Burlington High School in 1948. Former classmate Shirley Meacham said he did not attend the 30th reunion in 1978. She said that at the time he was listed as living in the Canary Islands off northern Africa.

The photograph that accompanied the claim of responsibility showed Tracy from the waist upward. Tracy, who is thin and of medium height, was wearing a dark blue shirt and was staring straight into the camera.

The photocopy of his passport said he was a native of Vermont, born in Rutland on Nov. 20, 1930, and unmarried. The passport was issued Sept. 3, 1981 and was valid until Sept. 2, 1986.

Six other Americans are missing in Lebanon.

The Revolutionary Justice Organization also has claimed responsibility for the abduction of James Cicippio, 56, of Valley Forge, Pa. He was kidnapped Sept. 12 from the campus of the American University of Beirut where he was acting comptroller.

Two other groups also claimed responsibility for Cicippio's abduction, but the Revolutionary Justice Organization was the only one to support its claim with a photograph of the hostage.

The group also has said it is holding three Frenchmen.

Islamic Jihad, another Shiite Moslem group, has said it kidnapped four Americans: Terry Anderson, 38, chief Middle East correspondent of The Associated Press; David Jacobsen, 55, director of the American University Hospital; Thomas Sutherland, 55, acting dean of agriculture at the American University of Beirut; and William Buckley, 57, political officer at the U.S. Embassy in Beirut.

On Oct. 4, 1985, an Islamic Jihad caller said Buckley had been killed after being ''tried'' for ''American intelligence crimes.'' A blurry photo purporting to show the body was made public, but no body was produced. Lebanese Shiite and Western intelligence sources said Buckley actually may have died earlier, possibly after being tortured.

Another group claims to be holding Frank Herbert Reed, 53, the American director of the Lebanese International School.

Twenty foreigners are missing in Lebanon - seven Americans, eight Frenchmen, two Britons, one Italian, one Irishman and one South Korean.