Brookfield has lodged a development application for a second office tower adjacent to its $500 million City Square skyscraper.

The plans are for a 16-level premium office tower with 30,000 square metres of net lettable area, with a targeted 5-star NABERS energy rating.

Brookfield is currently constructing a 45-level, 75,000sqm office tower, City Square, at the 123 St Georges Terrace site, and is also restoring the historic Newspaper House, which will deliver 7,000sqm of retail and food and beverage outlets.

The first City Square tower is 100 per cent pre-leased, with BHP Billiton taking up the lions share, Barrick Gold 5,000sqm and PwC 8,500sqm.

"We have strong interest in the proposed tower and are confident in the ongoing strength and growth of the Perth office property market," Brookfield Office Properties chief executive Brian Kingston said.