VIENNA, May 1 (Reuters) - Iran's chief nuclear negotiator said on Saturday Tehran expects U.S. sanctions on oil, banks and other sectors and on most individuals and institutions to be lifted based on agreements reached so far at talks in Vienna, Iranian state media reported.

Russia and Western European powers meanwhile gave contrasting accounts of the task ahead in the talks to bring Iran and the United States fully back into compliance with the 2015 nuclear deal, as the talks adjourned for six days.

"Sanctions...on Iran's energy sector, which include oil and gas, or those on the automotive industry, financial, banking and port sanctions, all should be lifted based on agreements reached so far," Deputy Foreign Minister Abbas Araghchi was quoted as saying by Iranian state media.

Araghchi did not say under which mechanism sanctions would be lifted or refer to how Tehran would meet Washington's demands and return to its commitments under the deal.

"We will negotiate until the two sides' positions come closer and our demands are met," he said. "If they are met there will be an agreement, if not there will naturally be no agreement."

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The U.S. State Department had no immediate comment on Araghchi's remarks.

President Joe Biden is seeking to return to the deal after Washington pulled out in 2018 under then President Donald Trump and reimposed sanctions against Tehran. Iran responded as of 2019 by breaching many of the deal's limits on its nuclear activities.

The talks began last month in Vienna with the remaining parties to the deal - Iran, Russia, China, France, Britain and Germany - meeting in the basement of a luxury hotel, and the United States based in another hotel across the street. Iran has refused to hold direct meetings with U.S. officials.

"We have much work, and little time, left. Against that background, we would have hoped for more progress this week," senior diplomats from the so-called E3 - France, Britain and Germany - said in a statement.

Officials have said they hope to reach a deal by May 21, when an agreement between Tehran and the U.N. nuclear watchdog on continued monitoring of some Iranian nuclear activities is due to expire.

"We have yet to come to an understanding on the most critical points. Success is by no means guaranteed, but not impossible," they added.

U.S. National Security Adviser Jake Sullivan said on Friday the talks were in "an unclear place," meaning it was uncertain whether they would lead to an agreement.

"We should not expect breakthroughs in the days to come," Russia's ambassador to the U.N. nuclear watchdog, Mikhail Ulyanov, told reporters after a meeting of the remaining parties that wrapped up the third round of talks, adding the talks would reconvene on Friday.

"We need simply to continue diplomatic, day-to-day work, and we have all the reasons to expect that the outcome, (the) final outcome, will be successful and it will come quite soon, in a few weeks," said Ulyanov, who is one of the more optimistic voices at the talks.

The break in talks was widely expected as diplomats said officials from several countries are also involved in the Group of Seven foreign ministers' meeting in London that begins on Monday and ends on Wednesday.

In his remarks, Araghchi said that "There are individuals and institutions that have been specifically sanctioned and their (the U.S.) list is long. Talks on the list are still ongoing." He added that under what had been agreed so far, more than a majority of the list would have the sanctions lifted.

(Additional reporting by John Irish in Paris and Dubai newsroom Writing by Francois Murphy Editing by John Stonestreet, David Holmes and Frances Kerry)