The Iranian, Brazilian, and Turkish foreign ministers agreed on Monday that Iran will swap in Turkey most of its 3.5%-enriched uranium for 20%-enriched fuel for use in its Tehran scientific research reactor.

The countries agreed that a letter be sent to the IAEA within one week to declare Iran is ready for fuel exchange, ISNA cited Iranian Foreign Ministry spokesman Ramin Mehmanparast as saying.

After the letter is received by the IAEA, an agreement between Tehran and the agency must be drawn up and signed.

"If Iran and [the] Vienna group sign the agreement, the fuel will be kept in Turkey's territory, so that it will be under Iran and the IAEA supervision," the agency quoted the Iranian official as saying.

The so-called Vienna group comprises Russia, France, the United States and the IAEA.

Mehmanparast earlier said some 1,200 kilograms of Iran's low-enriched uranium will be swapped.

Iran has been under international pressure to halt uranium enrichment, needed both for electricity generation and weapons production. Tehran has repeatedly rejected the demand, insisting it is pursuing a purely civilian program.

Several Western powers have called for harsher sanctions against Tehran if it does not agree to halt uranium enrichment.

Turkish Foreign Minister Ahmed Davutoglu said on Monday there was no need for sanctions against Iran after a nuclear swap deal has been agreed.

The signatories of the trilateral agreement reaffirmed Tehran's right "to develop research, production and use of nuclear energy (as well as nuclear fuel cycle including enrichment activities) for peaceful purposes without discrimination."

Iran has agreed to allow international inspections of its nuclear facilities to maintain the transparency of its nuclear program.