UPDATE: Part of St Georges Terrace has been closed to traffic after a fire started in a building in the central business district.
A Fire and Emergency Services spokesman said the fire was reported in a three-storey derelict building at 125 St Georges Terrace about 2.30pm near the back of the new BHP construction site. The fire, which is now under control, is believed to have started in the north-west corner of the property.
GALLERY: See more pictures of the scene
The fire was put out at 4.30pm, but crews will be on scene for the next few hours to mop up.
Fire incident controllers said the blaze was confined to the first floor of the building.
The site is undergoing a $500 million facelift which will include cafes, shops, offices and the new BHP Billiton tower. The strip has lain dormant for 20 years and will form part of the City Square development.
It is believed the fire is in the old Newspaper House building, which has been heritage listed and was home to The West Australian newspaper. The heritage listing included Newspaper House and its grand foyer, the Print Hall, built in 1910, and the neighbouring Royal Insurance building, 1890s WA Trustee building and Perth Technical School.
St John Ambulance are on stand-by at the scene, although the building is believed to be vacant.
All lanes westbound on St Georges Terrace remain closed between William Street and Mill Street, eastbound lanes have reopened. Police have requested the intersections of St Georges Terrace and William Street and St Georges Terrace and Mill Street to be placed on flashing amber. Main Roads said major delays can be expected.