Four journalists from a Nigerian independent daily on Thursday appeared in court over a story alleging President Umaru Yar'Adua was ill.The Leadership newspaper said early this month that the head of state -- whose health has been the subject of speculation since August -- was "critically ill."It reported that the president was unable to keep his official engagements for two days due to failing health and that specialist doctors had been flown in from Saudi Arabia.Yar'Adua's office immediately refuted the report insisting that he was healthy and working as normal.Prosecutors consequently arraigned the newspaper's publisher, two editors and a reporter.The four pleaded their innocence on charges of "defamation of character and injurious falsehood," and were granted 500,000 naira (4,240 US dollars) bail each.They were ordered to return to court on December 16.Yar’Adua’s state of health has been shrouded in secrecy since he became president in 2007.Speculation was fuelled in August when he travelled to Saudi Arabia officially for a short Muslim pilgrimage but spent some 16 days there without any official explanation.