BERLIN, Dec 6 (Reuters) - Germany wants Iran to present realistic proposals in talks over its nuclear programme, a Foreign Ministry spokeswoman said on Monday, adding that offers Tehran made last week almost all violate previously agreed compromises. Its proposals are "not a basis for a successful end to talks," she said. "We reviewed the proposals ... carefully and thoroughly and concluded that Iran violated almost all compromises found previously in months of hard negotiations." Iran and major powers started talks in April aimed at bringing Tehran and Washington back into full compliance with the 2015 pact, which was abandoned by former U.S. President Donald Trump three years ago. But negotiations stopped after the election of Iran"s hardline President Ebrahim Raisi in June. Indirect talks between Washington and Tehran on reinstating their nuclear pact resumed a week ago but broke off on Friday, with a resumption scheduled for later this week, as Western officials voiced dismay at sweeping Iranian demands. The German Foreign Ministry spokeswoman said it was unacceptable that Iran was advancing its nuclear capacity in parallel with the talks. She said Berlin wants to build on progress already made and remains "committed to the diplomatic path, but the window of opportunity is closing more and more". A senior Iranian official said on Sunday a U.S. reluctance to lift all sanctions that were reimposed on Iran by Trump is the main challenge to reviving the deal. Western powers have questioned Tehran"s determination to salvage the agreement. U.S. Secretary of State Antony Blinken said on Friday Washington would not let Iran drag out the process while continuing to advance its uranium enrichment programme and it will pursue other options if diplomacy fails.