Iran's nuclear programme is entirely peaceful, President Mohammad Khatami has said.
Experts question why resource-rich Iran needs nuclear power
"I emphasise that Iran is totally against any form of weapons of mass destruction and denounce as false and groundless the claims that Iran is producing nuclear weapons," he said.
The president was speaking as legal experts from the United Nations' nuclear watchdog held talks with Iranian officials on demands that Iran allow snap inspections of its nuclear sites.
Washington believes Iran is secretly developing nuclear weapons under the cover of a civilian programme based on Russian technology.
Iran insists its nuclear programme is to generate electricity and is for peaceful purposes only.
"Iran will not renounce the development of nuclear technology, one of the pillars of the power of the people," Mr Khatami said on Wednesday.
He was speaking during a meeting with Supreme Leader Ayatollah Ali Khamenei and other senior Iranians.
The European Union, Russia and the Japan have joined the US in urging Tehran to provide greater assurances that it is not developing nuclear weapons.
The International Atomic Energy Agency (IAEA) is pressing Tehran to sign up to an additional protocol of the Nuclear Non-Proliferation Treaty (NPT), which would allow no-notice inspections of the country's nuclear facilities.
The IAEA team arrived in Tehran on Monday. Talks so far have been "positive and constructive", Iran's official media has reported.
Iran has previously said it would only agree to snap inspections if it was granted more access to nuclear technology.
In June, the IAEA criticised Iran for failing to report activities related to its nuclear programme.
The IAEA is due to report again in September.
The EU has warned that relations with Iran would be reviewed if Tehran refused to co-operate with the IAEA and sign up to closer inspections.
Iranian politicians are divided over whether to allow more intrusive inspections and are facing a dilemma over how to respond to international pressure, says the BBC's Miranda Eeles in Tehran.
Some politicians have called on Tehran not to give in to the demands, arguing it would be better to pull out of the nuclear treaty altogether.
Nuclear experts have questioned the declared need of Iran - a country with vast oil and natural gas reserves - to produce nuclear energy.