UNITED NATIONS, - United Nations Secretary-General Ban Ki-moon announced on Friday that he would establish an internal UN board of inquiry to investigate a deadly attack on a humanitarian aid convoy in Syria and urged all parties to fully cooperate. 'The Board of Inquiry will ascertain the facts of the incident and report to the Secretary-General upon the completion of its work. The Secretary-General will review the report and decide what further steps to take,' UN spokesman Stephane Dujarric said in a statement.