TEHRAN, Sept. 3 -- President Mahmoud Ahmadinejad wants negotiations on Iran's nuclear program but won't halt uranium enrichment ahead of talks, U.N. Secretary General Kofi Annan said Sunday after meeting with the Iranian leader.

Annan's two-day visit to Tehran comes after Iran ignored a United Nations deadline to halt uranium enrichment by the end of August, opening the door to possible sanctions.

"On the nuclear issue, the president reaffirmed to me Iran's preparedness and commitment to hold negotiations" with Western powers to find a solution to the impasse over the country's nuclear program, Annan said at a joint news conference with Iranian Foreign Minister Manouchehr Mottaki.

However, Ahmadinejad "reiterated that he did not accept suspension before negotiations," the U.N. chief said, conveying Iran's rejection of a condition set by the five permanent members of the U.N. Security Council plus Germany.

Ahmadinejad did not attend the news conference or make any statements. On Saturday -- the first day of Annan's visit -- he reiterated at a rally that Tehran would continue its nuclear activities.

In June, Iran was offered a package of incentives to roll back its nuclear program. The Tehran government's lack of cooperation with U.N. inspectors has raised concerns it is trying to produce nuclear weapons, although it says its atomic program is peaceful, intended solely to generate electricity.

Iran's slowness in responding to the package prompted the Security Council to issue a resolution July 31 demanding that Tehran halt uranium enrichment by the end of August or face economic and diplomatic sanctions.

On Sunday, Mottaki said the council issued the resolution "under pressure from the United States and Britain" and described it as a "mistake" and a "black mark against them."

Iran did respond to the incentives package on Aug. 22, rejecting the stipulation that it stop enriching uranium before talks begin. The content of its response has not been made public.

Iran appeared more responsive to U.N. concerns regarding Lebanon, where it backs Hezbollah, the militant Islamic group that fought Israeli troops during a 33-day war.

Ahmadinejad "reaffirmed his country's support for the implementation of resolution 1701," Annan said, referring to the U.N. resolution that imposed a cease-fire and included measures to prevent the rearming of Islamic militias.

The U.N. chief did not disclose specifics of his talks on the topic with the Iranian president. After meeting with Annan on Saturday, Mottaki made a vague promise to support the resolution but did not directly mention Hezbollah.

Annan also reiterated his displeasure over an exhibit in Tehran of cartoons on the Holocaust. The exhibit is a response to Muslims' outrage over the publication last year and earlier this year of Danish cartoons depicting the prophet Muhammad.

Earlier Sunday, Iran's Foreign Ministry said the country planned to hold a conference this fall questioning evidence of the Holocaust. Ahmadinejad has dismissed the Holocaust as a myth, provoking an international outcry.

Annan arrived in the Iranian capital after visits to Lebanon, Israel and Syria. He is also scheduled to visit Qatar, Saudi Arabia, Egypt and Turkey.