DUBAI, April 27 (Reuters) - Shares in two Saudi banks that are in early merger talks moved in opposite directions on Thursday while other regional markets moved little in thin volumes.

Alawwal Bank extended the previous session's 8.6 percent gains, adding 0.9 percent after 20 minutes of trade. Shares in Saudi British Bank (SABB), however, slipped 0.2 percent after jumping 6.8 percent on Wednesday.

Other commercial lenders were mixed, with the top two by total assets, making small gains; National Commercial bank was up 0.3 percent and Al Rajhi Bank up 0.4 percent.

If Alawwal and SABB were to merge they would form the third largest bank by assets.

Petrochemicals, most of which have still to report earnings, were generally weak and were the main drag on the index, which was down 0.1 percent. Saudi Kayan Petrochemical fell 1.1 percent.

Dubai's index slipped 0.3 percent as 15 shares declined and 11 advanced.

Emaar Malls fell 4.4 percent as its shares went ex-dividend on Thursday. DAMAC Properties slid 1.2 percent, extending sharp losses from the previous session when it too traded ex-dividend.

Shares favoured by local day traders were among the top gainers, including investment firm Shuaa Capital which rose 1.7 percent.

In neighbouring Abu Dhabi, the index rose 0.1 percent, buoyed by a 0.5 percent gain in the shares of the largest lender First Abu Dhabi Bank.

Shares of Abu Dhabi National Energy , however, fell 3.3 percent. On Wednesday its shares had slumped as much as 6.7 percent on news that rating agency S&P had downgraded TAQA's credit rating to 'A-' from 'A' and gave it a 'negative' outlook from 'stable', but closed flat.

Qatar's index edged down 0.3 percent, heading back towards a four-month low hit earlier in the week. The country's largest petrochemical producer, Industries Qatar, fell 0.9 percent, wiping out some of the gains it made on Wednesday after announcing first quarter net profits grew by a third on the previous year.









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