DUBAI, July 25 (Reuters) - Poor corporate earnings, many of them the result of Saudi Arabia's austerity policies and sluggish economic growth, weighed on the Saudi stock market in early trade on Tuesday as regional bourses were generally soft.

The Saudi stock index edged down 0.1 percent as National Shipping Co (Bahri) sank 5.3 percent after reporting quarterly net profit plunged to 153.9 million riyals ($41.0 million) from 487.1 million riyals a year earlier, as revenues also tumbled. It cited lower shipping spot market rates and higher bunker costs.

Al Yamamah Steel lost 4.3 percent after reporting a quarterly profit of 17.2 million riyals, down from 67.9 million riyals, as sales fell steeply.

Saudi Arabia Fertilizers Co (SAFCO) dropped 2.6 percent after quarterly profit shrank to 204.3 million riyals from 302.3 million riyals and sales declined. And home appliance distributor Shaker tumbled 6.7 percent after swinging to a quarterly net loss as sales dropped sharply.

However, National Gas and Industrialization gained 2.6 percent after quarterly profit climbed to 37.8 million riyals from 23.0 million riyals. Dallah Healthcare edged up 0.6 percent after quarterly profit rose to 70 million riyals from 54.1 million riyals.

In Dubai, the index slipped 0.4 percent, hit by a 0.7 percent decline in blue chip Emaar Properties .

Telecommunications firm du rose only 0.5 percent after reporting a quarterly net profit of 446.6 million dirhams ($122 million), almost unchanged from a year earlier but well above forecasts of 373.2 million dirhams by SICO Bahrain and 409.3 million dirhams by EFG Hermes.

The results ended a major earnings slump; du had reported declining year-on-year profits in the preceding 10 quarters. Revenues rose from a year ago and the first-half dividend stayed the same.

Unusually, the two most heavily traded stocks were Islamic insurers, with Islamic Arab Insurance gaining 5.5 percent and Dubai Islamic Insurance soaring 11.5 percent.

Qatar's index dropped 0.4 percent as Qatar Gas Transport , the most active stock, fell 2.3 percent after saying first-half profit dropped to 408.3 million riyals ($112 million) from 500.3 million riyals, on the back of a much smaller decline in revenue.

(Reporting by Andrew Torchia; Editing by Susan Fenton) ((; +9715 6681 7277; Reuters Messaging: