MOSCOW — President Vladimir Putin said Wednesday there is no proof Iran is seeking to build nuclear weapons, but emphasized that Tehran must be encouraged to make its nuclear program fully transparent.

"We are sharing our partners' concern about making all Iranian programs transparent," Putin said at a news conference after talks with visiting French President Nicolas Sarkozy. "We agreed yesterday, and the president confirmed it, that Iran is making certain steps toward the international community to achieve that."

Putin is to make his first visit to Iran early next week for a summit of Caspian Sea nations.

Sarkozy said Putin's trip to Tehran could encourage Iran to be more cooperative. "After the trip, there could be a will to cooperate — that is essential," he said.

Russia has opposed the U.S.-push for tougher sanctions against Iran and called for more checks and inspections of Iranian facilities by International Atomic Energy Agency, the U.N. nuclear watchdog.

"We have worked cooperatively with our partners at the United Nations Security Council, and we intend to continue such cooperative work in the future," Putin said.

But he said that with no "objective data" showing Iran is developing nuclear weapons, "we proceed from an assumption that Iran has no such plans."

Iran's past clandestine activities — and its refusal to heed U.N. Security Council demands that it suspend uranium enrichment — have stoked suspicion among the U.S. and its allies that country is trying to create the fissile material for nuclear weapons. Iran says its nuclear program is intended only to develop an alternative source of energy.

The IAEA says that it has not been able to detect signs that Iran has a weapons program, but has withheld judgment on what the Islamic Republic's ultimate aims may be.

Sarkozy has hardened France's stance on Iran in recent months, shifting closer to the United States in his insistence on tough Security Council sanctions and even his mention of the possibility of war. While the U.S. and European nations are pressing for greater sanctions, Russia and China have resisted.

Sarkozy had criticized Russia of late, recently accusing it of "brutality" in exercising its energy dominance, and courting central and eastern European leaders who bristled at Moscow's renewed influence.

But on his first presidential visit to Russia, he struck a decidedly upbeat note after hours of talks with Putin on many touchy subjects.

Sarkozy pointed at the opportunities of bilateral cooperation in such areas as space and nuclear energy, and added that France wants to be a "privileged partner of Russia." Touching on France's presidency in the European Union next year, he said that Russia and Europe were "natural partners."

Speaking after talks with Putin, he pointed at the need for transparency and respect for free-market rules in the bilateral economic ties and promised to take a non-discriminatory attitude toward Russian companies willing to purchase assets in France.

Putin, questioned by reporters on Russian authorities' attitude toward non-governmental organizations, also sought to moderate his tone.

Western critics long have accused Putin of backsliding on democracy, muffling dissent and free media and harassing NGOs — claims the Kremlin has angrily denied. Sarkozy on Wednesday was set to meet with representatives of Russian NGOs.

Putin said Wednesday that NGOs were important and his government was trying to cooperate with them, but in a steely note warned against foreign interference in Russia's affairs: "It's bad when such organizations are being used by one state against others to achieve some goals."