Iran said Sunday that it accepted some parts of a Western offer aimed at getting Tehran to drop its nuclear program, but it rejected others while calling the central point ambiguous.

Iran said the key issue of uranium enrichment - a process that can make nuclear fuel for a power plant or fissile material for an atomic bomb - needed clarification.

Although the government did not give specifics, the comments were the first time Iran has said directly that it rejects or accepts parts of the package.

Top nuclear negotiator Ali Larijani said Iran would reject the package outright if Western powers threatened the Islamic republic with sanctions in the nuclear standoff.

The comments came as the United States and Europe lobbied other nations to join them this week in urging Iran to accept the offer - and warning of UN Security Council action if it does not - according to documents shared with The Associated Press in Vienna, Austria.

The package, presented by permanent Security Council members the United States, Russia, China, France and Britain, plus Germany, contains a series of incentives for Iran to suspend uranium enrichment, which would allow negotiations over its nuclear ambitions.

The incentives include promises that the United States and Europe will provide Iran nuclear technology and that Washington will join direct talks with Tehran.

Iran has not responded to the offer, and it underlined Sunday that it would not be rushed. Foreign Ministry spokesman Hamid Reza Asefi insisted Iran was not stalling over the package and would take "as long as is necessary" to study it.

He told a press conference the package includes "points which are acceptable. There are points which are ambiguous. There are points that should be strengthened, and points that we believe should not exist."

He did not give specifics.

Larijani said the offer of nuclear technology was a "positive point" but that "there are also points that are unclear, such as the uranium enrichment program."

"This has not been made clear yet to Iran, so these are things where the finishing touches must be made," he told reporters in Cairo, Egypt, after talks with President Hosni Mubarak and Arab League chief Amr Moussa.

Egypt is one of the members of the U.N. watchdog nuclear agency's board of directors, which the United States and Europe are lobbying to pressure Iran to accept the deal.

Larijani sharply denounced any threats of sanctions against Iran in connection with the package.

"We will not accept negotiations under pressure," he said.

He said the package, as presented to Iran, did not contain any threats of penalties.

The five permanent Security Council members and Germany are said to have worked out a set of possible sanctions if Iran rejects the proposal, but these were not mentioned when EU envoy Javier Solana presented the package to Iran last week to maintain a positive atmosphere.

The United States accuses Iran of seeking to develop nuclear weapons, which Tehran denies, saying its program seeks only to develop energy.

But the package drops demands for an all-out scrapping of enrichment, instead asking Iran to suspend such activity during the duration of any negotiations.

In two position papers shown to the AP, the United States and Europe were lobbying hard for support of the package from members of the 35-nation board of the International Atomic Energy Agency before a Monday meeting of the body.

"We are ... encouraging all board members to make firm statements to call on Iran" to negotiate on the six-power offer, the U.S. position paper said.

If Tehran declines, the text warned that the five permanent Security Council members plus Germany "have agreed to pursue measures, including at the U.N. Security Council, (to) pressure the Iranian regime to change course."

The other text, issued by Britain, France and Germany, also warned that if Iran remains defiant, "the Security Council will have no choice but to increase the pressure on Iran."

The texts were shared with the AP by diplomats accredited to the gathering.