CIA activities to prevent Salvador Allende from assuming the Chilean presidency in 1970 were more extensive than previously acknowledged in official accounts, author Seymour M. Hersh asserts in the December issue of Atlantic Monthly.

Hersh charges, based on the account of an unnamed "close associate" of then-CIA director Richard Helms, that President Nixon "specifically ordered the CIA to get rid of Allende" -- an order that Hersh contends amounted to a go-ahead to assassinate Allende if necessary.

"Helms told the associate there was no doubt in his mind at the time what Nixon meant," Hersh writes.

The "close associate," Hersh writes, was relating Helms' personal account of a Sept. 15, 1970, Oval Office meeting of Nixon and then national security adviser Henry A. Kissinger, who the source said later "pressured [Helms] again on the subject."

Helms testified in 1975 hearings before the Senate Intelligence Committee that Nixon's orders at that meeting referred to Allende's overthrow and did not "in his mind" include assassination.

Hersh's account, which is adapted from his forthcoming biography of Kissinger, does not contain the kind of smoking gun evidence that would drastically alter the picture drawn in the 1975 Senate hearings.

Testimony then revealed that the CIA financed an unsuccessful covert propaganda campaign against Allende's election, and later participated in various plots with Chilean politicians and military leaders to keep him from taking office after his plurality victory in September, 1970.

The article, however, has direct accounts from a half-dozen alleged participants in the Chile operations, including two deep-cover CIA operatives whose identities were previously unknown.

The agents, called "false-flaggers" by the CIA because of their use of false Latin American passports as cover, were veteran agents assigned to give CIA money and instructions to "extreme right-wing terrorists," including cashiered Gen. Roberto Viaux and other Chilean military leaders plotting against Allende, Hersh writes.

Viaux led a kidnaping attempt Oct. 22, 1970, that resulted in the murder of the head of the Chilean armed forces, Gen. Rene Schneider -- an operation the CIA has disavowed.

Hersh quotes the U.S. military attache in Chile at the time, Col. Paul C. Wimert Jr., as saying he "figured they [the false-flaggers] had been sent to Santiago to arrange for Allende's death."

According to the article, an aide in the National Security Council, Yeoman Charles E. Radford, told Hersh that he saw option papers that discussed ways to assassinate Allende. Hersh's article does not cite any evidence that plans to kill Allende were put into operation.