John Chilcot, the head of an inquiry examining the British role in the Iraq war, delivered his opening statement Tuesday, setting off another month of testimony in an investigation launched last year.
Michael Jay, a former senior civilian official at the Foreign Office, told the inquiry Wednesday that he felt a U.N. Security Council resolution authorizing military force in 2003 was a necessity, the BBC reports.
"I felt very uncomfortable with the prospect of a conflict without U.N. Security Council resolution," he said.
Washington and London gave up efforts to secure explicit U.N. authorization to invade Iraq because of opposition from veto-wielding members France and Russia.
Opponents of the March 2003 invasion said another resolution was needed to go to war. Legal advisers to former British Prime Minister Tony Blair said U.N. resolutions authorizing military force during the Persian Gulf War were still in effect, however.
The inquiry Wednesday received declassified legal advice given to Blair before the 2003 invasion. The government said it decided to release copies to the inquiry because of the "very exceptional" nature of the probe.