At least 50 major office projects are believed to have been either indefinitely suspended or cancelled.

Figures released yesterday by the Property Council Australia show the sharpest six-month jump in nationwide office vacancies in 17 years.

Developers have haemorrhaged millions of dollars by shelving major office projects in recent months because they fear a sharp fall in demand and further worsening of the financial crisis.

The national vacancy rate was 6 per cent at January 2009, compared with 4.2 per cent six months ago, according to council's Office Market Report.

The assumption in the industry is that next year's vacancy rates will be far worse, which means most projects that have not yet started will be scrapped or deferred.

The Australian