UPDATE 2-Brookfield Properties boosts offering size by 67 pct

* Says to sell 10 mln preferred shares at C$25 apiece

* Shares to yield 6.75 pct annually for first 5 yrs (Recasts, adds details, updates share movement)

Aug 31 (Reuters) - Brookfield Properties (BPO.TO) (BPO.N), one of Manhattan's biggest landlords, on Monday raised the size of its offering by 67 percent to 10 million preferred shares, and said it sees gross proceeds of C$250 million.

Earlier in the day, the company had announced its plans to raise C$150 million by selling 6 million preferred shares.

The company said it agreed to issue the shares to a syndicate of underwriters led by CIBC and Scotia Capital Inc at C$25 a share, and the proceeds would be used for general corporate purposes.

The preferred shareholders will be entitled to receive a cumulative quarterly fixed dividend yielding 6.75 percent annually for the initial five-year period ending Sept. 30, 2014, Brookfield said in a statement.

The offering is expected to close on or about Sept. 24, the company said.

Brookfield said underwriters will have an over-allotment option of 1.5 million preferred shares at the same price. If the over-allotment option is fully exercised, the total gross proceeds of the financing will be C$287.5 million.

Shares of the company closed down 36 Canadian cents at C$12.04 Monday on the Toronto Stock Exchange. (Reporting by Koustav Samanta and Ashutosh Joshi in Bangalore; Editing by Maju Samuel)