FRANKFURT, Feb 10 - The European Central Bank said on Tuesday foreign currency reserves of the euro zone central banks in the week ending February 6 fell by a net 1.7 billion euros, while its gold holdings were unchanged. The net position of the ECB and euro zone central banks in foreign exchange reserves totalled 174 billion euros at the end of the reporting week, the ECB said in its regular weekly consolidated financial statement. The change was due to customer and portfolio transactions, the ECB said. Gold reserves were unchanged at 130.344 billion euros, the bank said.//