By Celine Aswad

DUBAI, Aug 20 (Reuters) - Most stock markets in the Gulf rose modestly on Sunday, lifted by a rally in oil prices at the end of last week, while three small to mid-sized Saudi Arabian insurers fell sharply after they were slapped with a temporary ban by the central bank.

Riyadh's index .TASI added 0.4 percent as all but two of the 14 listed petrochemical producers advanced after Brent oil LCOc1 surged 3.3 percent on Friday. Rabigh Refining and Petrochemical 2380.SE rose 1.6 percent.

Saudi Indian Company for Cooperative Insurance 8110.SE dropped 3.8 percent, Malath Cooperative Insurance 8020.SE fell 4.5 percent and Arabian Shield Cooperative Insurance 8070.SE slumped 7.6 percent.

The central bank said it was temporarily banning those insurers from selling vehicle policies because of "serious breaches" in their car insurance practices.

Another insurer, Sabb Takaful 8080.SE , closed up 0.2 percent. Saudi British Bank 1060.SE (SABB) announced that it had signed an agreement to buy all of HSBC's HSBA.L shares in the insurance company for 117.8 million riyals ($31.4 million), taking SABB's total ownership in the insurer to 65 percent.

The deal, which is pending board and regulatory approvals, is expected to be completed in the second half of this year. Shares of SABB fell 0.7 percent.

In the United Arab Emirates, Dubai's index .DFMGI rose 0.4 percent on the back of gains in stocks that were volatile last week.

Union Properties UPRO.DU , the most heavily traded share on Sunday, jumped 4.3 percent to 0.898 dirham. Last week the Motor City developer reported a big quarterly loss as it fixed accounting errors; the stock has now regained the level where it was trading before the announcement of the loss.

"Funds with excess cash have been chasing alpha and not fundamentals," said a Dubai-based fund manager. "In such an environment it would be hard to call any trend or direction."

Abu Dhabi's index .ADI closed flat in thin trade; Dana Gas DANA.AD rose 3.3 percent, while Abu Dhabi National Energy TAQA.AD lost 1.6 percent on profit-taking from last week's jump.

Banking shares were robust in Doha, helping lift the index .QSI 0.3 percent higher. Commercial Bank COMB.QA gained 1.2 percent.

Egypt's index .EGX30 fell 0.7 percent as shares of El Sewedy Electric SWDY.CA lost 1.3 percent on profit-taking. In the previous two sessions they had jumped 9.3 percent after the company reported a 72 percent jump in its second-quarter net income and proposed a cash dividend of 8 Egyptian pounds per share.

HIGHLIGHTS



SAUDI ARABIA



* The index .TASI rose 0.4 percent to 7,209 points.



DUBAI



* The index .DFMGI added 0.4 percent to 3,615 points.



ABU DHABI



* The index .ADI flat at 4,493 points.



QATAR



* The index .QSI rose 0.3 percent to 9,134 points.



EGYPT



* The index .EGX30 fell 0.7 percent to 13,026 points.



KUWAIT



* The index .KWSE added 0.2 percent to 6,901 points.



BAHRAIN



* The index .BAX gained 1.0 percent to 1,312 points.



OMAN



* The index .MSI rose 0.5 percent to 4,913 points.

(Editing by Andrew Torchia and Richard Balmforth) ((celine.aswad@thomsonreuters.com)(+971 5 6224 7653)(Reuters Messaging: celine.aswad.thomsonreuters.com@reuters.net))