German industry expects a steep rise in exports to Iran following the lifting of international sanctions, and Economy Minister Sigmar Gabriel said on Sunday he would seek to drum up trade on visit Tehran in early May.Iran ended years of economic isolation when world powers lifted the crippling sanctions against the Islamic Republic on Saturday in return for Tehran complying with a deal to curb its nuclear ambitions. "That was faster than expected," said Reinhold Festge, head of German engineering trade group VDMA, adding that now diplomats had delivered it was the turn of companies and banks to seize the new opportunity.For decades before sanctions were imposed, Germany was Iran's biggest trading partner. The gap in Iranian imports from Germany and other Western countries has largely been filled by Chinese, Korean and Middle Eastern competitors.Germany's Chambers of Commerce and Industry (DIHK) said it expected exports to Iran to double to 5 billion euros ($5.5 billion) in the coming years and reach twice that figure in the long term.This could compensate, at least partially, for waning demand for German goods from China, Russia and other emerging markets."German companies have lost important market share in Iran. We must revive German-Iranian ties as quickly as possible," DIHK head Volker Treier said.Economy Minister Gabriel, who led the first top level German government visit to Tehran in 13 years in July, will head back to Iran in early May to co-chair an economic conference with his counterpart Ali Tayyebnia.