A senior advisor to Iran's Supreme Leader Ayatollah Ali Khamenei said the five permanent members of the UN Security Council plus Germany (P5+1) must recognize Iran's "natural right" to develop peaceful nuclear technology, the Press TV reported on Thursday.

"Given that the Islamic republic has always proven its goodwill in nuclear talks and its commitment to the International Atomic Energy Agency (IAEA), the P5+1 must also recognize Iran's natural right to attain peaceful nuclear energy," Ali-Akbar Velayati was quoted as saying.

Velayati added that Iran's nuclear rights should be recognized also because the Islamic republic is a committed signatory to the Nuclear Non-Proliferation Treaty (NPT), said the report.

Iran's chief nuclear negotiator Saeed Jalili wrote a letter to EU foreign policy chief Catherine Ashton over the upcoming nuclear talks to be held in Russia's capital Moscow, said Press TV.

In his letter, Jalili "voiced doubts about the six world powers ' determination to hold fruitful talks with Iran in Moscow," according to the report.

"The Islamic Republic of Iran is ready to hold progressive talks for cooperation based on a clear logic and specific initiatives," he said.

Jalili, who is also Iran's Supreme National Security Council ( SNSC) Secretary, stated that unless the P5+1 gear up for meetings at experts and deputies level, holding further talks merely for the sake of discussions would be of no avail, said Press TV.

The Baghdad talks on Iran's nuclear standoff concluded last month with a plan to hold another round of talks in Moscow on June 18-19.

Meanwhile, China and Russia called for a peaceful resolution to Iran's nuclear issue through dialogue and negotiation, according to a joint statement released Wednesday.

The statement was issued during Russian President Vladimir Putin's three-day state visit to China, where he also attended the 12th Meeting of the Council of Heads of Member States of the Shanghai Cooperation Organization.

China and Russia oppose the use of, or threats of using, force on the issue, said the statement, adding that they do not agree on exerting excessive pressure and imposing any unilateral sanctions against Iran, but advocate efforts to promote peace and facilitate talks on Iran's nuclear issue.

On Wednesday, Iran accused the IAEA of conducting secretive intelligence activities.

The accusations were made by Iranian ambassador to IAEA Ali- Asghar Soltanieh on the sidelines of the IAEA Governors conference in Vienna, Austria, where he accused the IAEA of using secretive means to obtain information on Iranian facilities.

Soltanieh criticized in particular Western councillors and media for speculation about a possible secret atomic weapons program. He reaffirmed the "solely peaceful" aims of Iran's nuclear program.

On Friday a bilateral meeting is planned in which access for IAEA experts to Iran's facilities, documents, and nuclear experts will be discussed.