DUBAI, April 18 (Reuters) - Dubai's stock market rose sharply in a broad-based rally early on Tuesday but other Gulf bourses were sluggish, with Saudi Arabian banks mixed after first-quarter earnings announcements.

The Dubai index gained 1.3 percent to 3,509 points, rebounding from near technical support on its March low of 3,435 points. All 10 most heavily traded stocks rose with GFH Financial, the most active, adding 3.6 percent.

Abu Dhabi dropped 0.7 percent, however, because of a 2.3 percent fall by telecommunications firm Etisalat as it went ex-dividend.

Qatar's index was flat but Commercial Bank of Qatar lost 1.4 percent after reporting a 66.7 percent drop in first-quarter net profit to 91.2 million riyals ($25.1 million).

Analysts polled by Reuters had on average forecast CBQ would make net profit attributable to equity holders, a slightly different profit measure, of 209.4 million riyals; the bank cited a sharp rise in provisions for non-performing loans.

Saudi Arabia's index slipped 0.3 percent as Alawwal Bank fell 1.4 percent after reporting a quarterly profit of 324.0 million riyals ($86.4 million), down from 511.5 million riyals a year earlier. NCB Capital had projected 376 million riyals and EFG Hermes, 443 million riyals.

But National Commercial Bank, the kingdom's largest lender, gained 0.5 percent after reporting a 2.7 percent rise in first-quarter net profit to 2.70 billion riyals; SICO Bahrain had forecast 2.39 billion riyals.

National Metal Manufacturing and Casting Co surged 3.9 percent after saying it had signed a memorandum of understanding with Saudi National Automobiles Manufacturing to make automobile parts. It did not give details, but developing an auto industry is a goal of the Saudi government's economic reform programme.

(Reporting by Andrew Torchia Editing by Jeremy Gaunt.) ((andrew.torchia@thomsonreuters.com)(+9715 6681 7277)(Reuters Messaging: andrew.torchia.thomsonreuters.com@reuters.net))