Germany rejected Thursday criticism from Israel over a deal to export gas-liquefaction equipment to Iran, dpa reported.
Officials in Berlin said Steiner Prematechnik Gastec had won export clearance at the end of February for the deal, reportedly worth 100 million euros (160 million dollars).
The three systems are to cool and compress natural gas into liquid form so it can be transported by ship to export customers.
A spokesman for the Economics Ministry in Berlin said petrochemical plant was not restricted by UN trade sanctions imposed on Iran on account of its nuclear-research programme. He said Steiner had obtained the permit properly.
The Israeli Foreign Ministry voiced exasperation Thursday at the permit, saying it breached the "spirit" of the UN sanctions.
This week the Simon Wiesenthal Centre appealed to Berlin to prohibit the deal. Jewish groups have criticized the contract, charging that Germany is fostering economic relations with Iran despite that nation's nuclear program and its threats toward Israel.
The Berlin spokesman said the permit was issued by the federal export controls agency BAFA after careful study established that the plant had no military applications. "At that point there was no legal grounds to forbid the export," he said.
Steiner, based in the western city of Siegen, has been hired to build the three plants on the southern Iranian coast.
Liquefied natural gas (LNG) is transported by ocean when there are no pipelines to transport gas at ambient temperature. The European Union had encouraged the LNG trade to reduce Europe's dependence on piped Russian natural gas.
At the start of July, French oil company Total pulled out of a deal to develop gas fields in Iran because of political tensions.