Brookfield Office Properties Inc. on Monday extended for another week its cash tender offer to purchase all outstanding preferred shares of MPG Office Trust Inc.

Brookfield, which hopes to close its acquisition of the downtown Los Angeles office building owner by the end of the month, has seen resistance from some MPG shareholders to its $25-a-preferred-share offer. A group of preferred shareholders said in a July lawsuit said the tender offer did not reflect the value of dividends they say they should have received since 2008, when the struggling real estate investment trust suspended dividend payments.

Common shareholders, who are to receive $3.15 a share, approved the deal in July.

Brookfield and MPG first announced the acquisition in April, and Brookfield launched its tender offer in June. It has since extended the deadline for preferred shareholders to tender their shares several times. The most recent deadline was to expire today and has now been extended until Sept. 16.

The total deal is valued at $2.2 billion, including assumption of about $1.9 billion in debt plus the net cash proceeds from the recent sale of MPG’s U.S. Bank Tower.