DUBAI - Shares of Abu Dhabi-listed Dana Gas fell sharply early on Monday, before a London court hearing on its maturing sukuk issue, while Qatar bucked an otherwise weak regional market.

They stocks sank 2.7 percent after 90 minutes of trade, heading to their third straight session of losses, as investors awaited the outcome of a London High Court trial on the validity of the $700-million sukuk.

It focuses on Dana Gas's June announcement that it would not redeem its outstanding sukuk, or Islamic bonds, on the grounds that due to changes in interpretation of Islamic finance they're no longer sharia-compliant and therefore unlawful in the UAE.

The Abu Dhabi index was down 0.5 percent, as most other shares declined.

The Dubai index lost 0.9 percent as 19 shares declined and only three rose; Emaar Properties was down 2.1 percent.

Qatar's index, which has been struggling to recover from declines triggered by its diplomatic rift with four Arab states in early June, was up 0.6 percent. Islamic lender Masraf Al Rayan was up 2.2 percent.

The Saudi index lost 0.7 percent as most 14 of the 20 most valuable shares fell. The largest, Saudi Basic Industries lost 1.2 percent.

(Reporting by Celine Aswad; Editing by Andrew Heavens) ((celine.aswad@thomsonreuters.com)(+9715 62247653)(Reuters Messaging: celine.aswad.thomsonreuters.com@reuters.net))