A senior Iranian official says next week's nuclear talks with the major powers from the U.N. Security Council could be the "last chance" for the West because Tehran's atomic capability is improving, according to Reuters.

Tehran's nuclear ambassador Ali Asghar Soltanieh claims Iran may not return to negotiations if next week's nuclear talks fail in Istanbul.

"It might be the last chance because by installing fuel rods produced by Iran in the core of the Tehran Research Reactor, probably parliament will not allow the government to negotiate or send its uranium outside the country and the Istanbul meeting might be the last chance for the West to return to talks," the nuclear ambassador told the IRNA news agency, according to Reuters.

Bruno Tertrais, Senior Research Fellow at the Foundation for Strategic Research in Paris, believes Soltanieh is just putting on a show.

"Mr. Solanieh's argument is reversible. We could always say it's the last chance for Iran," Tertrais told Reuters.

Western diplomats do not expect a breakthrough in next week's nuclear talks with Iran.