The global economic crisis has cost Arab countries $2,500bn (£1,690bn) in the last four months alone, according to Kuwait's foreign minister.
Sheikh Mohammed al-Sabah told reporters in Kuwait City that oil-rich Gulf Arab states had postponed or cancelled 60% of development projects.
He did not give details for his figures, which were released days before an Arab Economic Summit.
Stock market falls and a low oil price have contributed to the losses.
The biggest loss was an estimated 40% drop in the value of Arab investments abroad, which had previously totalled around $2.5tn, AFP news agency reports.
"The Arab world has lost $2.5 trillion in the past four months," Mr Sabah said after meeting fellow foreign and finance ministers.
Kuwait City is due to open a two-day Arab Economic Summit on Monday, the first of its kind.
Arab League Secretary General Amr Moussa
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