Tehran cannot accept a U.N.-brokered proposal to transfer the bulk of its low-enriched uranium out of Iran with the aim of converting it into fuel for use in a medical research reactor amid political pressure from the United States and European countries, according to visiting nuclear negotiator Saeed Jalili.

"As long as a political touch is added to a business deal, we cannot accept it. In addition, strong pressure is being imposed," Jalili, Iran's top nuclear negotiator, said in an interview Monday in Tokyo.

Rejection of the proposal may lead to further sanctions against Iran.