BRUSSELS - The European Union will re-impose asset freezes on several Iranian companies, annulled this year by court order, even as world powers appear close to a breakthrough deal with Tehran over its contested nuclear program.EU diplomats said the move was to re-establish sanctions already imposed, rather than increasing pressure on Iran. Any new sanctions could risk scuppering a deal that global powers hope to reach with Iran at talks that start next Wednesday.President Barack Obama has called on the US Congress not to impose new sanctions on Iran - which the West accuses of developing nuclear weapons technology - while the talks are under way. The EU decision, taken by senior officials on Thursday, must still be approved by EU governments later this week, diplomats told Reuters. It covers Persia International Bank, Export Development Bank of Iran and Bank Refah Karagan, among others.It aims to counter mounting litigation by hundreds of people and companies from Iran after several legal challenges succeeded in quashing sanctions this year.It is the first time the EU has sought to address legal challenges by imposing new measures against previously listed targets, instead of trying to win appeals, and reflects growing concern that sanctions can be difficult to defend in court."We are maintaining the current sanctions regime, not broadening it. The relistings amount to keeping the current system," one EU diplomat told Reuters, speaking on condition of anonymity.In striking down sanctions, Europe's second-highest court has said EU governments have failed to provide sufficient evidence to link targeted companies with Tehran's nuclear work. The EU has in the past appealed against sanctions being quashed, for example after the court overturned sanctions on Bank Mellat and Bank Saderat, among the biggest private banks in Iran, earlier this year.Diplomats now say a growing body of litigation makes it difficult to find legal bases for appeals.They say it is impossible to provide detailed proof of the targeted companies' links to Iran's atomic program because doing so could expose confidential intelligence.Iran denies it is seeking nuclear weapons and says its nuclear work is for energy and other peaceful applications.At talks in Geneva last week, six world powers - the United States, Russia, China, France, Britain and Germany - came close to agreeing preliminary concessions with Iran, but failed to clinch a deal. The parties meet again next week.