The Dubai government and its affiliated firms owe non-financial Japanese companies roughly $7.5 billion in credit that had not been collected as of October 31, a study by the Japanese government showed.

The study covered 18 projects that involved Japanese general contractors, trading companies and electric machinery manufacturers, said the Nikkei business daily.

The figure includes public works projects, such as subways and roads, commissioned by the Dubai government, it said. It does not include bank loans.

It said some $1 billion of the accounts receivable have gone unpaid past their due dates, with some more than a year overdue.

Some of the delay is blamed on disagreements about which party should shoulder the costs that have over-run initial estimates, it said.

Fears that Dubai's debt problems are not limited to troubled state conglomerate Dubai World battered investor confidence in the world's top oil-exporting region and sent shares across the Gulf tumbling again on Thursday.-Reuters