The crisis at property giant DTZ deepened today as the troubled firm warned that losses this year will be far greater than expected.

Chief executive Paul Idzik, who was poached from Barclays in November, said business at the company, one of London's biggest property consultants, has deteriorated significantly this year amid "unprecedented and turbulent market conditions".

The former banker, a mediator between Barclays chief executive John Varley and president Bob Diamond in his time at the bank, admitted that losses for the year to the end of April will be "significantly greater than previously expected". The company last year made £20.6 million.

DTZ shares tumbled 11¾p or 30% to 28p, having peaked above 800p a little over two years ago. They were suspended at one stage today because of the scale of the fall.

It was the second profit warning in four months for DTZ, which has suffered from plunging property prices, a collapse in transactions, and its ill-timed £40 million takeover of rival Donaldsons at the top of the market.

The debt-ridden firm was forced to go to its shareholders for help, and in January raised £48.7 million in a rights issue.

French family-owned shareholder SGP Investors took on more than half the offer to ensure it succeeded.

DTZ was today worth just £65 million. It has already axed 250 jobs in a £30 million cost-saving scheme.

Idzik said it can save a further £20 million in 2009-10, putting dozens more jobs at risk. The company suffered a 17.5% fall in revenue in the first half of the financial year - the six months to 31 October - and losses of £9 million.

Idzik, a dual US and British citizen, today pinned his waning hopes on a better second half, arguing that it usually delivers a higher proportion of its annual revenues.

"The global economic environment has continued to deteriorate, with a correspondingly negative impact on confidence and levels of activity in the commercial property market," he said.

"This has resulted in a decline in commercial property investment transaction levels, exacerbated by the lack of availability of debt finance.

"In addition, activity in the occupational property markets has similarly decreased, with the deteriorating economic environment affecting tenants' decisions."