The European Central Bank said on Tuesday foreign currency reserves of the euro zone central banks in the week ending May 7 rose by a net 0.1 billion euros while its gold holdings fell. The net position of the ECB and euro zone central banks in foreign exchange reserves totalled 174.9 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 fell one million euros to 136.528 billion euros, the bank said. The drop was due to a technical adjustment carried out by one euro zone national central bank, it added.///