BT Investment Management's chief executive, Dirk Morris, will leave the fund manager next Monday rather than on October 1 as announced last week.

A BTIM statement on the Australian Securities Exchange this morning gave no reason for the move, saying only that chairman Brian Scullin would assume the role of executive chairman, taking responsibility for day-to-day management of the company.

Morris resigned at the same time as presenting a three to five-year strategic plan to BT Investment Management's board, saying he himself could not commit to the plan’s timeline.

Executive search firm Egon Zehnder has been appointed to undertake an international search for the new chief executive for BTIM.