WASHINGTON (AP) _ Of the two kinds of nuclear technologies Iran wanted from Russia _ reactors and gas centrifuges _ the centrifuges provide a more direct path to nuclear weapons.

A centrifuge is an intricately designed cylinder used to separate, or enrich, uranium for use either in nuclear bombs or as fuel for a civilian power reactor. Iran does not have the know-how to make centrifuges on its own.

There has been speculation that the Russians never actually planned to sell a centrifuge plant to Iran but floated the idea simply to have a concession to hand President Clinton at this week's U.S.-Russian summit in Moscow.

But a copy of a Jan. 8, 1995 protocol of Russian-Iranian negotiations on nuclear supply arrangements says the two parties intended to work out a deal for a centrifuge plant _ plus a number of other forms of future nuclear cooperation.

The copy of the protocol was obtained by the Natural Resources Defense Council, a private anti-nuclear group, and provided to news organizations Wednesday. Christopher Paine of the council said his group got it from the Russians.

The protocol said that besides the agreement for Russia to complete construction of a nuclear reactor at Bushehr, near the Persian Gulf, the two parties would prepare and sign four additional contracts. The three were described as:

_Construction of a centrifuge plant for enrichment of uranium ``according to conditions'' comparable to those included in Russian contracts concluded with other countries. Negotiations on this contract were to begin within six months, in conjunction with a deal for the construction of a ``uranium vault.''

At various times recently, both Russian and Iranian government officials have denied there was a centrifuge deal. The language of the protocol indicates that, technically, there was no contract yet but negotiations were planned.

_Delivery of a light-water nuclear reactor for research purposes. The reactor would have a power rating of 30 to 50 megawatts, which is large for research purposes. It is to be delivered to Iran's Organization of Atomic Energy within three months.

_Delivery of 2,000 tons of natural uranium from Russia during the first three months of this year.

_Training at Russian academic institutions for 10 to 20 Iranian nuclear scientists per year. Iran's envoy to the International Atomic Energy Agency, Mohammad Sadegh Ayatollahi, told The Associated Press last week in New York that up to 40 Iranian physicists and engineers were receiving training in Moscow.

The Russian-Iranian protocol said the two sides had agreed on conditions for completing one nuclear reactor at Bushehr. The Germans had started building a two-reactor complex there in the 1970s but then abandoned the project.

The light-water reactor Russia still plans to build for Iran will yield plutonium, although it would have to be purified and machined to make a bomb. Iran says it wants the reactor to produce electricity, not make plutonium for nuclear weapons.

Clinton said after his meeting with President Boris Yeltsin on Wednesday that he still wished Russia would drop the reactor deal. But he indicated he was pleased that Yeltsin had agreed to forgo the planned arrangements for a centrifuge plant.

The modern centrifuge was pioneered by the Russians after World War II with the help of German scientists. It is about the size of a scuba tank. Inside the vacuum-tight casing is a fast-spinning rotor tube that separates the isotopes of uranium.

Either uranium or plutonium can be used as the main ingredients in a nuclear bomb.

Paine, of the Natural Resources Defense Council, said there could be little question that Iran's interest in acquiring centrifuges was for military purposes.

``If you're just starting out in the (civilian) nuclear business it doesn't make any economic sense to invest in an enrichment plant,'' Paine said.

Reactor fuel can be purchased on the open market at a much lower cost, he said.