Raising the stakes ahead of Thursday’s rare meeting, 239 lawmakers signed a statement expressing support for negotiations based on proposals put forward by Iran, which do not mention Tehran’s own nuclear programme.

The United States has made clear it will focus on Iran’s nuclear activities, which the West fears are aimed at making bombs, in the meeting in the Swiss city.

Iran, which insists its programme is aimed solely at producing electricity, has offered wide-ranging security talks but says it will not negotiate on its nuclear “rights.”

“We remind the negotiating countries that this is an historic opportunity which can be a way out of the current deadlock and solve the problems,” the MPs said in a statement quoted by state broadcaster IRIB.

“We recommend the 5+1 (six powers) to use this historic opportunity,” it said. “If the group of 5+1 repeats past mistakes instead of using this opportunity, the Iranian parliament would take other decisions as it did in the past.”

In 2006, the Iranian parliament passed a bill obliging the government to review the level of its cooperation with the U.N. nuclear watchdog after the United Nations approved sanctions on Tehran over its atomic programme.