"There are individuals with radical views in US Congress and there are authorities that could introduce new sanctions against Iran. This is what our primary concern is," Hamid Baidinejad, who is also Iran's chief negotiator at the nuclear talks with the P5+1 group of international mediators, said.
"Iran will still keep developing its nuclear program," Baidinejad said.
The negotiator pointed out that the P5+1 group, comprising Russia, the United States, the United Kingdom, France, China and Germany, and Iran were making every effort to reach an agreement on the nature of the country's nuclear program.
At November 2014 talks in Vienna, the negotiating parties again failed to work out a comprehensive deal, agreeing instead to extend the deadline for reaching an agreement to July 2015.