Tens of thousands of Italians, many waving rainbow-coloured peace banners, marched silently through Rome on Saturday to demand the release of a left-wing journalist kidnapped in Iraq. Giuliana Sgrena, who writes for Communist daily Il Manifesto, was seized in Baghdad on Feb. 4 while carrying out interviews. Sobbing and wringing her hands, Sgrena appeared on a video this week pleading for her life. "Today's march shows that the entire nation is close to Signora Sgrena," said Romano Prodi, leader of Italy's centre-left opposition bloc and former president of the European Commission. Organisers said 500,000 people joined the protest, which snaked its way past the Colosseum down to the ancient chariot track, the Circus Maximus, for a rally and music concert. There was no immediate official estimate of crowd numbers. The march under grey skies took on obvious political overtones, with many demonstrators calling on Prime Minister Silvio Berlusconi to withdraw Italian troops from Iraq.