UNITED NATIONS, SEPT. 16 -- Secretary General Javier Perez de Cuellar reportedly told the Security Council today that Iran's leadership had offered a tacit halt in its war with Iraq but would announce acceptance of a formal cease-fire only after an international commission established Iraq's guilt in starting the conflict.

This conditional acceptance of the council's unconditional cease-fire demand was rejected by Iraq, which reaffirmed that it would honor the July 20 resolution if Iran does, Perez de Cuellar is said to have reported.

The secretary general briefed the 15 council members in a closed meeting upon his return from a week-long trip to Tehran and Baghdad. Afterwards, at an impromptu press briefing, he refused to reveal the specifics of what he was told, saying the council members had insisted "that what I just told them was secret."

Perez de Cuellar did say that the Iranian leaders he met -- Foreign Minister Ali Akbar Velayati, Prime Minister Mir Hossein Mousavi, President Ali Khamenei and parliamentary Speaker Hojatoleslam Ali Akbar Hashemi Rafsanjani -- took a common position. "They said the same exact thing. They have stated a unified position. I think that was very important."

Diplomats who attended the council briefing said Perez de Cuellar left delegates with his written summation of the Iranian position, which indicated that Iran would silently honor a cease-fire but would announce its acceptance only "at the conclusion of the commission's work."

U.S. officials said such a stance would enable Iran to break the lull in fighting simply by rejecting the commission's conclusions as flawed. What remains to be seen, the Americans said, is whether other council members would find the Iranian position as unacceptable as Iraq and the United States have found it.

A diplomat from a nation that has been reluctant to support U.S. proposals for an arms embargo against Iran, and has urged time for further clarifications, said today that Perez de Cuellar's report still leaves the Iranian stand "more or less unclear."

The secretary general, however, indicated his view that Iran's offer is as specific as it will get by telling reporters that as far as he is concerned "the answers were very clear," and as a result "now the council members know the positions of both countries." It is now up to the council to act, he insisted.

The original council resolution demanded an immediate cease-fire and a withdrawal to frontiers "without delay." .