By Louis Charbonneau and Parisa Hafezi
LAUSANNE, Switzerland (Reuters) - Western powers are hoping for concessions from Tehran that could help clinch a political agreement in nuclear talks this week after the United States and European powers voiced a willingness to compromise on suspending U.N. sanctions, officials said.
U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif had been due to meet in Lausanne, Switzerland, later on Sunday to try to break the logjam ahead of a crucial round of talks between Iran and six major powers.
But a senior U.S. State Department official later said that meeting would be delayed until Monday due to extensive U.S.-Iranian consultations earlier on Sunday between nuclear and Foreign Ministry officials.
Kerry has urged Iran to take decisions now to enable them to clinch a political framework agreement for a nuclear deal with Tehran that would lift sanctions in exchange for curbs on Tehran's nuclear program ahead of an end-March deadline. The parties have set a June 30 deadline to finalize an accord.
"Serious gaps still remain," Deputy Iranian Foreign Minister Abbas Araqchi was quoted by Iran's ISNA student news agency as saying. "We have had progress in the recent talks and during this round of talks we will see whether more progress can be achieved."
"We hope to narrow the gaps on important disputes," he added.
Kerry told CBS news on Saturday he hoped "in the next days" it would be possible to reach an interim political deal with Iran if Tehran can show that its nuclear power program is for peaceful purposes only.
It is not yet clear when the talks between Iran and the six powers will begin in Lausanne.
Reuters reported last week that the United States and five other powers and Iran have begun talking about a possible draft resolution to endorse any future deal and address the lifting of U.N. sanctions. The U.N. penalties could be eased quickly in the event of an agreement, Western officials said.
Officials close to the talks said this was a major new concession on the part of the United States, which had long insisted that U.N. sanctions would remain in place for years to come after a nuclear deal was signed, while unilateral U.S. and European measures might be lifted more swiftly.
"This was a quite a shift in the U.S. position and we hope the Iranians will follow with concessions on their end," a Western official told Reuters on condition of anonymity. "So far the concessions have been mostly one-sided, though there has been some limited progress recently."
Iranian officials have privately welcomed the new position on U.N. sanctions in the talks on the part of the United States and France. Diplomats say the other members of six power group back the idea of a swift suspension of U.N. nuclear sanctions if there is a deal, though they caution that many U.N. restrictions would stay in place.
"Iran knows that it will not happen overnight, but the fact that it is being discussed at the (six powers') capitals and having a resolution is a sign of their willingness to resolve the issue," a senior Iranian official told Reuters.
Iran, which rejects Western allegations it wants an atomic weapons capability, wants the U.N., EU and US sanctions lifted all at once. A nuclear accord that ends the decade-long standoff with Iran is seen as crucial to reducing tensions in the region.
Officials on both sides of the talks said it will be very difficult to get a political agreement this week. Iranian officials say that a signed agreement this week is unlikely, though they do not rule out some kind of verbal understanding.
Some eight U.N. resolutions dating back as far as 2006, four of them imposing sanctions, demand that Iran freeze uranium enrichment and other sensitive atomic work. They also bar the country from buying and selling atomic technology and anything linked to ballistic missiles. There is also a U.N. arms embargo.
In his CBS interview, Kerry also redoubled his criticism of Republicans, who said that seeking U.N. Security Council resolutions that endorse any deal and lift U.N. sanctions before seeking approval of Republican-led Congress would be wrong.
He said a letter from 47 Republicans to Iran's leadership warning that any deal with President Barack Obama bypassing the Senate would not be binding and could be rescinded later was an unprecedented intrusion on executive authority.
Kerry voiced the hope that the letter would not undermine the negotiations in Lausanne.
The State Department said on Friday that any lifting of U.N. sanctions would not impact unilateral U.S. sanctions or limit Washington's ability to take action on its own against Iran in the future.
(Additional reporting by Lesely Wroughton; Editing by Giles Elgood and Alison Williams)