* Four of top 10 gainers in Saudi are cement stocks
* Saudi market down for third day on profit-taking
* Dana Gas drops on sukuk legal case
* Qatar flat after Arab alliance meets
* Egypt's EFG Hermes surges from four-month low
DUBAI, July 6 (Reuters) - Shares in Saudi Arabia's cement and steel sectors rose on Thursday after the government cut export tariffs, but Gulf stock markets were mostly weak after a slide in oil prices.
The Saudi government said it was cancelling all export duties on steel for two years to encourage local industries, and would halve cement export tariffs.
Analysts said top-line growth of cement and steel companies was not expected to get a huge boost, but the news was positive for a building materials sector that has been hit hard by the government's austerity policies in the past couple of years.
"Despite some companies having obtained a licence to export six months ago, competition from other Asian markets is stiff and the demand outlook is relatively subdued," said a Riyadh-based cement sector analyst.
"Any rise in exports will still do little to reduce the supply glut in the local market."
Najran Cement, one of the companies with an export licence, rose 2.6 percent in its heaviest volume since February and three other stocks among the top 10 gainers were also from the cement industry. Al Yamamah Steel Industries climnbed 1.7 percent.
The Riyadh index, however, fell 0.9 percent, its third straight session of losses. The banking sector was the main drag with heavyweight National Commercial Bank dropping 0.6 percent to 50.50 riyals, pulling further away from a 22-month intra-day high hit of 58.00 riyals on Sunday.
Elsewhere, Qatar's index edged down 0.1 percent as 21 shares rose and 12 declined. Foreign funds, which have been net buyers of Qatari shares this week, were neutral on Thursday while non-Qatari Gulf investors were net sellers, bourse data showed.
Four Arab states decided in a meeting in Cairo on Wednesday not to slap fresh sanctions on Qatar for now, but voiced disappointment at its "negative" response to their demands and warned of the possibility of further action against Doha.
The index is down 10.1 percent since June 5, when the diplomatic crisis erupted. Fund managers believe further sanctions, such as a pull-out of bank deposits, remain quite possible in coming days or weeks, but they may hurt the Qatari economy rather than cripple it.
In Abu Dhabi, Dana Gas fell 1.4 percent after sources told Reuters that London's High Court planned to hold a full hearing in September on efforts by the company to restructure $700 million of its Islamic bonds.
A High Court judge upheld an interim injunction there blocking holders of the sukuk, due to mature in October, from enforcing claims against Dana. But he also ordered Dana to cancel an injunction in a court in the emirate of Sharjah and seek a stay of its proceedings there.
The Abu Dhabi index edged down 0.4 percent.
In Dubai the index lost 0.5 percent in very low volumes, hit by a 1.4 percent drop in blue chip Emaar Properties and a 1.8 percent fall in peer DAMAC Properties .
Cairo's stock index rose 0.3 percent in quiet trade as 16 blue chips advanced and 13 declined. Credit Agricole Egypt jumped 6.9 percent in thin volume and inevstment bank EFG Hermes surged 2.9 percent from a four-month low.
* The index lost 0.9 percent to 7,204 points.
* The index fell 0.5 percent to 3,401 points.
* The index declined 0.4 percent to 4,396 points.
* The index edged down 0.1 percent to 8,923 points.
* The index edged up 0.3 percent to 13,370 points.
* The index added 0.1 percent to 6,680 points.
* The index fell 0.1 percent to 1,311 points.
* The index rose 0.1 percent to 5,120 points. (Editing by Andrew Torchia)