Reporting from Beirut — Iranian officials trumpeted new nuclear and military ambitions Monday in the face of domestic political discord and stepped-up international talk of tightening economic sanctions against the Islamic Republic.

Ali Akbar Salehi, head of Iran’s Atomic Energy Organization, announced that Tehran had informed the United Nations’ nuclear watchdog that it intended to launch construction of 10 new nuclear-fuel plants in the Persian calendar year starting March 2010 and begin producing 20%-enriched uranium to provide fuel for a Tehran medical reactor.

Up until now, Iran has only produced reactor-grade 3.5%-enriched uranium and has managed to build only one functioning nuclear-fuel plant.

“The 20% enrichment begins on Tuesday under supervision of inspectors and observers from the International Atomic Energy Agency,” or IAEA, Salehi said in an interview published on the website of Iran’s state-owned Al-Alam television news channel.

As of Monday morning, diplomats and arms inspectors in Vienna, home to the IAEA, had yet to receive anything in writing, said an official in the Austrian capital who spoke on condition of anonymity.

Western diplomats have vowed to pursue tougher sanctions against Iran to pressure it into curbing sensitive components of its nuclear and missile programs that they suspect are the cornerstones of an eventual atomic-weapons capability.

Iranian military officials also announced plans to build new military planes, aerial drones and anti-aircraft missiles in a flurry of pronouncements hailing national achievements ahead of annual commemorations of Iran’s 1979 Islamic Revolution on Thursday, when a burgeoning opposition movement and security forces are expected to clash on the streets of Tehran and other cities.

The eight-month political crisis continues to divide the Iranian political establishment. The Fars news agency, close to the Revolutionary Guard, reported that pro-government Iranians had signed a petition demanding the arrest of opposition leaders Mir-Hossein Mousavi, a former prime minister; Mehdi Karroubi, a former parliament speaker; and Mohammad Khatami, a former president.

Another official hinted at upcoming purges of the nation’s security forces. “Well-known intelligence and military elements were instrumental in the post-election sedition,” said intelligence minister Heydar Moslehi, according to the news website Aftabnews.ir .

Experts and international inspectors have concluded that Iran’s nuclear program has been stagnant in the months since the country’s domestic political crisis erupted following the reelection of President Mahmoud Ahmadinejad. Any move to escalate the program could alarm Western nations and Israel.

Iran lacks a plant to turn enriched uranium into fuel plates for the medical reactor. Few experts believe it has the infrastructure to build 10 enrichment facilities any time soon.

Ahmadinejad ordered Salehi to produce the 20%-enriched uranium fuel on Sunday. Salehi said the fuel would be produced at Iran’s Natanz enrichment facility but left the door open to a compromise.

Western officials accuse Iran of failing to respond to a U.N.-backed offer to transfer the bulk of Iran’s low-enriched uranium abroad in exchange for 20%-enriched fuel plates to power the ailing Tehran medical reactor. Iranian officials say they want to conduct the fuel exchange on their own soil, a condition the West has rejected.

Salehi said Tehran’s move to further enrich uranium was only meant to help cancer-stricken Iranians.

“We will stop enrichment as soon as we get the necessary fuel for the reactor,” he said.

daragahi@latimes.com