Federal Transport Minister John Baird has been subpoenaed to testify at the bribery trial of Ottawa Mayor Larry O'Brien.

After an eight-month Ontario Provincial Police investigation, O'Brien was charged in December 2007 with pretending to have influence with the government of Canada or with a minister of the government, contrary to Sec. 121 of the Criminal Code.

He was also charged with negotiating an appointment, influencing or negotiating appointments or dealing in offices, contrary to Sec. 125 of the Criminal Code.

The charges concern allegations that O'Brien — while running for mayor in the summer of 2006 — offered to help his opponent in the race, Terry Kilrea, get a job on the National Parole Board if Kilrea dropped out of the running.

The mayor's trial starts April 27.

Kilrea and the president of the Ottawa Labour Council, Sean McKenny, have also been subpoenaed to testify.

The Crown is expected to call more than two dozen witnesses in a trial that's expected to last nine weeks.

O'Brien responded to the charges when they were first laid.

"While I am personally very embarrassed that I have to face these charges, in a real sense it is a relief to finally get to the point where the truth will be determined in a court of law," he said, adding that the past year of "rumour, gossip and media headlines" had been hard on him and his family.

"Quite frankly, I believe with every fibre in my being that I am innocent."

He added that he feels lucky to live in Canada, where accused are presumed innocent until proven guilty.

The criminal charges did not place O'Brien under any legal obligation to resign.