Iranian president Hassan Rohani has once again declared that his country will not allow western powers to dictate Tehran's nuclear agenda.

Addressing a ceremony to mark Iran's accomplishments in the field of medicine, the Iranian leader said Tehran would not accept nuclear discrimination or apartheid.

Rohani told the gathering: "Their [west's] claim that Iran has secret activities is a blatant lie. If we wanted to be secretive, we wouldn't attempt to purchase centrifuges at global markets. Neither would we negotiate with international companies during the process of fuel production and uranium enrichment.

"We have nothing to put on the table and offer to them but transparency. That's it. Our nuclear technology is not up for negotiation. Iran will not retreat one step in the field of nuclear technology... we will not accept nuclear apartheid."

The moderate cleric said the country would not push for the production of nuclear weapons.

"At the present time that Tehran is able to enrich uranium even up to 20% degree and can meet demands of its nuclear facilities, it will not retreat from its peaceful nuclear activities," he said.

Iran is set to hold fresh negotiations with the world's major powers over its contentious nuclear activities from 13 May in Vienna. The next round of talks is aimed at bringing about a permanent solution to the standoff.

Rohani also took the opportunity to condemn the western nations for supplying chemical and biological weapons to the previous Iraqi administration in support of the war against Iran.