UPDATE 1-Gildan CEO to assume role a month earlier as activist investor pressure mounts

(Adds response from Browning West in paragraph 5)

Jan 12 (Reuters) - Vince Tyra will assume his role as CEO of Gildan Activewear from Jan. 15, nearly a month in advance, as the Canadian apparel maker grapples with activist investor pressure following the ouster of co-founder Glenn Chamandy.

Tyra, a former executive at Warren Buffett-owned apparel maker Fruit of the Loom and CEO of Broder Bros, was slated to take over as CEO at Gildan on Feb. 12.

Gildan's board said Tyra had "made himself available" to take the position earlier than was announced in December last year, "to respond to requests to engage early with key stakeholders."

The board has been under pressure from several key shareholders including U.S.-based activist fund Browning West and Turtle Creek Asset Management to reinstate Glenn Chamandy as Gildan's CEO, and terminate Tyra's appointment.

"It is clear to us – and presumably our fellow shareholders – that Gildan's board is trying to use Vince Tyra's accelerated start date to defy shareholders who have clearly rejected Mr. Tyra and to shift attention away from our requisitioned special meeting," Browning West told Reuters in an emailed statement.

Turtle Creek did not immediately respond to requests for a comment.

Earlier this week, Browning West sought to gain a majority on the company's board, and requested a special meeting to be held in order to reconstitute the board.

Gildan's board, on the other hand, said it was investigating "new information" around Chamandy's exit, including his engagement with some shareholders before his termination.

(Reporting by Juveria Tabassum; Editing by Krishna Chandra Eluri)