(Updates with comments on Saddam's trial, Iraq's unity) By Anna Mudeva SOFIA, Jan 29 (Reuters) - Iraq's foreign minister said on Thursday Saddam Hussein's weapons of mass destruction, which inspectors have failed to find, were carefully hidden but Hoshiyar Zebari said he was confident they could be discovered. "I have every belief that some of these weapons could be found as we move forward," Zebari, an Iraqi Kurd, told a news conference in Sofia. "They have been hidden in certain areas. The system of hiding was very sophisticated." The United States and Britain cited Iraq's possession of chemical and biological...