"Fordow will never be closed, and it will continue its work," Alaeddin Boroujerdi, chairman of the National Security and Foreign Policy Commission, said Wednesday.
"We in the parliament will not allow such a thing to happen."
Bouroujerdi's statements came amid reports in the West Iran is preparing a package of proposals that includes halting the 20 percent production of enriched uranium, a key demand by the United States and other Western powers, ahead of talks in Geneva next week, The Tehran Times said.
Iranian Foreign Minister Javad Zarif will present a proposal at the Geneva meeting with the P5+1 countries -- Russia, the United States, China, Britain, France and Germany -- that will focus on resolving the nuclear dispute, the Times said.
Earlier this week another Iranian lawmaker said the Fordow underground facility was fully operational, the semi-official Fars news agency reported.
"The centrifuges at Fordow have been installed completely and the facility is in full operation," Mohammad Esmayeel Kosari, a member of the parliamentary commission, told Fars.