DUBAI (Reuters) -- World powers should focus on scrapping nuclear weapons and abiding by their own non-proliferation commitments rather than speculating about Iran's peaceful atomic work, the Iranian foreign ministry said on Tuesday.

The broadside by the ministry's spokesman Ramin Mehmanparast appeared to be a response to a US call the previous day for Iran to take "urgent practical steps" to build confidence ahead of nuclear talks with six major powers in Baghdad on May 23.

"Some countries say they are concerned that Iran's activities might be diverted towards non-peaceful purposes in the future," he said. "When they are talking about future speculation, how can they not be concerned about scrapping nuclear weapons at the present time?"

Indirectly rebuking some of the nations involved in nuclear negotiations with Iran -- the United States, Russia, China, Britain, France and Germany -- Mehmanparast spoke of their own "contravention and clear violation" of the rules.

"Some of these countries have nuclear-capable submarines they have delivered to the Zionist regime," he said, alluding to Germany's sale of Dolphin-class submarines to Israel, which some analysts say can carry nuclear warheads.

"All of these countries need to feel committed to the contents of the nuclear non-proliferation treaty."

US officials have previously suggested Iran should build confidence by accepting more intrusive UN inspections, curbing its uranium enrichment work and closing a nuclear site near Qom.

Iranian officials have said the Baghdad meeting should lead to the lifting of sanctions imposed by the United States and its allies against Iran's energy and banking sectors.

The United States suspects Iran of seeking to develop a capacity to build nuclear weapons and has refused to rule out military action if negotiations fail. Iran denies this and maintains it has the right to enrich uranium and develop a peaceful nuclear program as a member of the NPT.

Last week, Iran's envoy to the International Atomic Energy Agency, Ali Asghar Soltanieh, said Tehran would never suspend enrichment, which can have both civilian and military purposes, and saw no reason to close the Fordow underground site which it has used to expand higher-grade enrichment.

The IAEA and Iran will hold talks in Vienna on May 14-15 after two meetings earlier this year failed to make headway.

The UN nuclear watchdog wants Iran to address questions raised in an IAEA report in November on suspected Iranian research and development activities relevant to nuclear weapons.

Iran has dismissed the allegations as fabricated.