Iran's supreme leader Thursday strongly rejected proposals for direct talks with the United States, effectively quashing suggestions for a breakthrough one-on-one dialogue on the nuclear standoff and potentially other issues.

The statement posted on Ayatollah Ali Khamenei's website echoes previous remarks opposing bilateral talks with Washington in parallel with stop-and-start nuclear negotiations with world powers, including the U.S., which are scheduled to resume later this month.

But the latest comments marked Khamenei's first reaction since the idea of direct talks received a high-profile boost earlier this week from U.S. Vice President Joe Biden during a security summit in Munich attended by Iran's foreign minister.

Khamenei's statement also could spill over into the upcoming negotiations in Kazakhstan between Iran and a six-nation group comprising the permanent U.N. Security Council members plus Germany. His apparent references to U.S. sanctions _ saying Washington was "holding a gun" to Iran _ suggests Iranian envoys will likely stick to demands for relief from the economic pressures before considering any nuclear concessions.

American proposals for direct dialogue with Iran received a cautious welcome Sunday from Iran's Foreign Minister Ali Akbar Salehi, but with caveats that Washington needs to quiet its "threatening rhetoric" for the offer to get real consideration by Tehran's ruling clerics.

All major decisions in Iran must be cleared by Khamenei, who has previously opposed direct negotiations with Washington and has shown no inclination of changing his positions.

"Talks will not solve any problems," Khamenei said in the statement posted Thursday following a meeting with air force commanders.

"You are holding a gun against Iran saying, `Talks or you'll fire.' The Iranian nation will not be frightened by such threats," he added in apparent reference to U.S. sanctions over Iran's nuclear efforts.

Washington has indicated in the past that it's prepared to talk directly with Iran on the nuclear issue, but so far nothing has come of it. Meanwhile, the wider talks between Iran and world powers have made little headway. Three rounds last year ended in stalemate with Tehran pushing for a roll back of Western sanctions in exchange for any key concessions on its nuclear program.

The West and allies fear that Iran's uranium enrichment labs could eventually produce weapons-grade material. The Islamic Republic claims it only seeks nuclear fuel for energy reactors and medical applications.

The U.S. and Iran broke ties after the storming of the American Embassy in Tehran in the wake of the 1979 Islamic Revolution. Iranian militants held 52 American hostages for 444 days.

"I am not a diplomat. I am a revolutionary and I express my words honestly," Khamenei was quoted as saying.

He noted that some factions inside Iran seek the direct U.S. talks due to their "naivety." He did not elaborate, but called for the need to challenge U.S. efforts to return "domination" over Iran _ a reference to the pro-Western shah that was toppled by the Islamic Revolution.

Khamenei, however, has shown some flexibility in the past over contacts with Washington. Iran and the U.S. have taken part in talks regarding Iraq and Afghanistan.