AIRO -- Iran's president, Mahmoud Ahmadinejad, ordered the nation's atomic energy agency on Sunday to begin producing a special form of uranium that can be used to power a medical reactor in Tehran, but that could also move the country much closer to possessing fuel usable in nuclear weapons.

The announcement Sunday came after several days of conflicting signals from Mr. Ahmadinejad and other Iranian officials about whether they were ready to reopen negotiations about giving up much of their country's fuel in exchange for enriched uranium from another country. The exchange would allow Iran to meet some of its energy needs, but would ease fears in the West because the fuel sent to Tehran would be in a form that would be very difficult to use in a bomb.

The deal fell apart when it was rejected by the leadership in Tehran.

Mr. Ahmadinejad's order on Sunday may represent nuclear gamesmanship; it is unclear if the country has the capacity to enrich its fuel to roughly 20 percent, from about 5 percent, as Mr. Ahmadinejad was ordering. Doing so would require retooling the configuration of the nation's centrifuges at a moment when Iran appears to have run into considerable technical difficulties at its nuclear plants.

It is unclear if those troubles have been caused either by its own technical failings, or sabotage by Western intelligence agencies, or both. American intelligence officials have told Congress and close allies, in closed briefings, that covert efforts to interfere with Iran's production capability are extremely active.