DUBAI, Jan 11 (Reuters) - Saudi Arabia's stock market fell on Wednesday morning with all but one petrochemical producer retreating after oil dropped near a one-month low overnight, while Dubai pulled back on profit- taking.

The Saudi index was down 0.7 percent to 6,957 points, falling below technical support at the mid-December low of 7,002 points. Two straight closes below support would confirm a break, triggering a double top formed by the December and January peaks and pointing down to around 6,770 points.

But Yanbu National Petrochemical Co (Yansab) rose 0.9 percent after it reported a 53.4 percent rise in fourth-quarter net profit to 602.85 million riyals ($160.7 million), in line with analysts' forecasts.

All major Saudi banks were weak, with Al Rajhi dropping 0.8 percent.

Dubai's main index , which has been outperforming the region since the start of the year, lost 0.5 percent as large-cap shares weighed on the market. Emaar Properties fell 1.0 percent.

But some shares in the insurance sector outperformed with Islamic Arab Insurance , the most heavily traded stock, jumping 4.1 percent. There is speculation that the finance and insurance industries may witness further tie-ups following the impending merger of National Bank of Abu Dhabi and First Gulf Bank .

Abu Dhabi's index lost 0.2 percent, dragged down by a 2.1 percent decline in blue chip Abu Dhabi Commercial Bank and a 0.8 percent fall in Aldar Properties .

(Reporting by Celine Aswad; Editing by Andrew Torchia, Larry King) ((celine.aswad@thomsonreuters.com; +971 4 4536886; Reuters Messaging: celine.aswad.thomsonreuters.com@reuters.net))