Alan Bishop, COI's new chief executive, has held peace talks with Charles Skinner, the director of communications at the DoT, in an attempt to halt a war of words over which department provides better value for money.
Skinner persuaded transport ministers to break away from COI last year and set up a separate roster.
Bishop said: "We had a friendly and constructive meeting. We agreed that we are not going to have a confrontational relationship."
Both sides are awaiting the findings of an inquiry into the breakaway by the Advisory Committee on Advertising, which should determine which department provides the best value.