Six powers seeking new sanctions against Iran hoped to persuade all 15 nations on the U.N. Security Council to back the proposed punitive measures.
France's U.N. Ambassador Jean-Marc de La Sabliere said that "a large majority" of the nations support the resolution drawn up by the United States and its European allies — Britain, France and Germany — along with Russia and China.
"I think we will be in a position to make some concrete proposals and changes in order to reach a unanimous Security Council," he said after talks late Wednesday in New York. The full council was scheduled to meet again late Thursday.
Full agreement is important because it would give the vote more weight.
The six nations fear Tehran wants enriched uranium to make nuclear weapons and have demanded it cease production. Iran has ignored them, despite the Security Council's first set of sanctions in December.
Iran's top leader said Wednesday that his country will respond with "illegal actions" if the council imposes still more sanctions.
"Until today, what we have done has been in accordance with international regulations," Ayatollah Ali Khamenei said. "But if they take illegal actions, we too can take illegal actions and will do so."
He did not elaborate on what those actions might be, but Iran is a signatory to the Nuclear Nonproliferation Treaty under which U.N. nuclear officials inspect its facilities. Some lawmakers and clerics have urged the government to respond to sanctions by withdrawing from the treaty.
Iran says it will never give up its right under the treaty to enrich uranium, insisting it needs alternative energy sources for when its oil reserves run out. The process can produce fuel for a reactor or fissile material for a nuclear warhead.
"If they want to treat us with threats and enforcement of coercion and violence, undoubtedly they must know that the Iranian nation and authorities will use all their capacities to strike enemies that attack," Khamenei said in a speech marking the start of the Persian New Year.
The latest sanctions would ban Iranian arms exports and freeze the assets of 28 additional individuals and organizations involved in the country's nuclear and missile programs.
The package also calls for travel restrictions on people subject to sanctions, on arms sales to Iran, and on new financial assistance or loans to the Iranian government.
The existing sanctions ban countries from providing Iran with materials and technology that could contribute to its nuclear and missile programs, and freeze assets of 10 key Iranian companies and 12 individuals related to those programs.
The U.S., Britain and France are hoping for a vote by the end of the week, but that could be difficult. South Africa, which holds the rotating Security Council presidency, wants extensive changes — including eliminating the arms embargo — and a 90-day hiatus on all sanctions.
The U.S. and its allies made clear Wednesday they would not agree to South Africa's proposed "time-out," a suggestion Britain's U.N. Ambassador Emyr Jones Parry called "totally perverse."
Acting U.S. Ambassador Alejandro Wolff indicated Washington also would reject a request by Indonesia and Qatar for the resolution to call for a nuclear-free Middle East, as that implicates Israel.
But Russia's U.N. envoy, Vitaly Churkin, said Moscow regarded the Indonesian and Qatar proposals "positively."
"I think there is general understanding in the Security Council that unanimity is going to be very important," Churkin said.
In a related development, European and U.S. officials who declined to be named said Tuesday that Moscow has told Tehran it would not ship fuel for the Russian-built Bushehr nuclear power plant in southern Iran until Tehran freezes uranium enrichment.
Russian Foreign Minister Sergey Lavrov denied that Wednesday.
"It's not the first time that we are seeing such an unscrupulous approach aimed at driving a wedge between us and Iran," he told lawmakers in the lower house of parliament.
Russia has said plans to supply fuel for Bushehr this month were called off because of the failure of Iran to make its payments.
Iranian President Mahmoud Ahmadinejad has asked to speak to the Security Council just before it votes.
In his own New Year's address, he accused world's powers of waging "psychological warfare ... to block our nation's progress."
Iran has offered to provide guarantees that its nuclear program won't be diverted toward weapons.