Iran has hardened its stance less than a week before the deadline for a nuclear deal, with its top leader rejecting a long-term freeze on nuclear research as a constitutional body on Wednesday approved a law banning access to military sites and scientists.

Ayatollah Ali Khamenei also insisted that Iran will only sign a deal if international sanctions are lifted first, which could further complicate the negotiations. The new law calls for all sanctions to be lifted the first day of any agreement’s implementation.

The supreme leader has backed his negotiators amid criticism from hard-liners. But his latest remarks may narrow their room to maneuver ahead of a self-imposed June 30 deadline for a potentially groundbreaking deal with world powers that would curb Iran’s nuclear activities in exchange for lifting sanctions.

Iran’s constitutional watchdog, known as the Guardian Council, ratified the legislation banning access to military sites and scientists, making it binding law, according to state TV.

The bill would still allow for international inspections of Iranian nuclear sites within the framework of the Nuclear Non-proliferation Treaty.

The United States — which is negotiating the deal alongside Britain, France, Russia, China and Germany — has said the sanctions would be gradually lifted as inspectors verify Iran’s compliance.

Speaking Tuesday night in comments broadcast on Iranian state TV, Khamenei said demands that Iran halt the research and development portion of its nuclear program constitute “excessive coercion.”

“We don’t accept a 10-year restriction. We have told the negotiating team how many specific years of restrictions are acceptable,” Khamenei said. “Research and development must continue during the years of restrictions.”

Khamenei said the U.S. is offering a “complicated formula” for lifting sanctions. He said that waiting for the U.N.’s International Atomic Energy Agency to verify Tehran’s cooperation would take too long.

“Lifting sanctions can’t depend on implementation of Iran’s obligations,” he said.

Khamenei also said he rejects any inspection of military sites or allowing Iranian scientists to be interviewed. Iran’s nuclear scientists have been the target of attacks.

The Americans’ “goal is to uproot and destroy the country’s nuclear industry,” he said. “They want to keep up the pressure and are not after a complete lifting of sanctions.”

White House Press Secretary Josh Earnest said there were still some “difficult challenges” to be met for any agreement, but he said “what we’re most focused on are the actions, not the words.”

He added that such actions include Iranian cooperation with “intrusive inspections.”

Western nations have long suspected Iran is covertly pursuing a nuclear weapons capability alongside its civilian program, charges denied by Tehran, which insists its atomic program is for purely peaceful purposes.

Negotiations likely will begin in earnest in the coming days in Europe. On Wednesday, Iran’s official IRNA news agency reported that deputy foreign ministers Abbas Araghchi and Majid Takht-e-Ravanchi had resumed talks with Helga Schmidt, a deputy of European Union foreign policy chief Federica Mogherini. It did not elaborate.

(AP)