The merit of an outline nuclear deal with world powers depends on tough details being settled in coming months, Iran's newspapers said yesterday, with opinions split on the planned agreement.

Conservative outlets maintained their long-held scepticism about negotiations with the United States and other powers, but rather than criticise the process outright many questioned who had benefited from recent talks in the Swiss city of Lausanne.

Iran's supreme leader Ayatollah Ali Khamenei, who will have the final say on any deal, has yet to officially comment on the agreed framework for ending the 12-year crisis over Tehran's nuclear programme.

Saturday's newspapers were the first in Iran since the announcement in Lausanne Thursday, as none were published during the two-week Nowruz holiday period, which has now ended.

"Lausanne Horse-Trading: Bargain or Bust?" asked the front page headline in Kayhan, a hardline conservative daily. Its downbeat editorial argued that Iran had received less than it had given away.

"The agreement speaks of suspension of sanctions and not the lifting of them," wrote editor Hossein Shariatmadari, who is directly appointed by Khamenei.

"Things that Iran has accepted are clear and verifiable, but what the other side has agreed is vague and subject to interpretation," he added.

French Foreign Minister Laurent Fabius drew attention Friday to the sanctions issue not being settled and noted that Iran would "still have to go all the way" on a deal.

On a similar note, German Foreign Minister Frank-Walter Steinmeier cautioned: "It's too early to celebrate."