* May marks worst month for region's share markets since January

* Saudi rebounds but volumes are the lowest since October 2015

* Yansab and SABIC lead petrochemical shares up on positive news

* Dubai recovers earlier losses as mid and large cap shares rise

* Abu Dhabi, Qatar edge lower

By Celine Aswad

DUBAI, May 31 (Reuters) - Share market indexes in the Middle East diverged on Tuesday, with Saudi Arabia's index outperforming peers as some positive news lifted shares, but all markets ended with losses for the month.

Riyadh's index rebounded 1.4 percent, ending three sessions of declines, although volumes were the lowest since last October.

The index was down 5.3 percent in May, its worst monthly performance since the start of the year.

Market heavyweight Yanbu National Petrochemicals (Yansab), jumped 6.5 percent after the company announced late on Monday that its proposed interim dividend was increased to 1.5 riyals per share, a 50 percent increase on the same period last year.

"We expect the company to pay a dividend of 2.5 riyals per share in 2016, and based on this the dividend yield is expected to be 6.3 percent," NCB Capital said in a note.

Total dividends in 2015 and 2014 were two and three riyals respectively.

Meanwhile Saudi Basic Industries climbed 2.5 percent, after the company said on Monday it had signed an agreement with Shenhua Ningxia Coal Industry Group to build a petrochemical complex in China.

"The markets were caught in a lull for the past several sessions and although activity remains quiet markets were driven today by some positive news about SABIC's new deal in China and the ability of companies to continue paying out dividends despite negative pressure on the bottom line," said a Riyadh-based portfolio manager.

Yamamah Steel , which was listd on the exchange this month, surged 6.6 percent after the company said it will pay a cash dividend of 1.5 riyals per share. This prompted investors to buy shares in other shares, such as Saudi Cable , which climbed 4.5 percent.

Dubai's index managed to recover earlier losses and edged up 0.2 percent, but closed down 5.1 percent for the month, its first monthly loss since January.

Air Arabia, the only listed airliner in the Gulf, climbed 3.1 percent while Emaar Properties, the largest listed real estate developer, rose 0.2 percent.

In Cairo, the main index gained 0.4 percent in this week's highest trading volumes, with both local and regional traders buying Egyptian shares, bourse data showed.

Oriental Weavers Carpet rose 1.1 percent despite the company posting a 38 percent drop in profits to 94.167 million Egyptian pounds ($10.60 million).



ABU DHABI, QATAR

Abu Dhabi's indexslid 0.2 percent in thin trade, taking its monthly losses to 6.5 percent.

Banking shares, the largest sector by market value, were a mixed bag. The largest lender by market cap, First Gulf Bank lost 1.3 percent while the second largest, National Bank of Abu Dhabi gained 2.5 percent.

Etisalat , the largest stock by market value and a constituent of the MSCI emerging market index , added 0.6 percent.

Fellow MSCI emerging market index constituent Qatar Gas Transport also gained, adding 3 percent. But Doha's index slid 0.1 percent.



TUESDAY'S HIGHLIGHTS



SAUDI ARABIA

* The index rose 1.4 percent to 6,448 points.



DUBAI

* The index added 0.2 percent to 3,314 points.



ABU DHABI

* The index dropped 0.2 percent to 4,250 points.



QATAR

* The index declined 0.1 percent to 9,539 points.



EGYPT

* The index edged up 0.4 percent to 7,483 points.



KUWAIT

* The index gained 0.4 percent to 5,400 points.



OMAN

* The index fell 0.5 percent to 5,811 points.



BAHRAIN

* The index added 1.6 percent to 1,111 points.

($1 = 8.8799 Egyptian pounds) (Editing by Larry King, Greg Mahlich) ((celine.aswad@thomsonreuters.com;+971 562 247 653 Reuters Messaging: celine.aswad.thomsonreuters.com@reuters.net))