The European Central Bank has warned consumers in the Eurozone to watch out for hidden price hikes as retailers prepare to switch to the euro. The warning was prompted by a study revealing prices of products changed into euros had risen 4.4% when dual pricing was widely introduced in the spring. Food hikes were driving the upsurge. Of 1,000 goods monitored by a German research institute from April to July, the switch prompted a rise in 86% of cases. With the euro price more prominent, customers do not notice the price in Deutschmarks or Francs in small print has gone up. From January retailers are legally obliged to use a fixed exchange rate. {{NEWS }}