DUBAI, Aug 29 (Reuters) - Most Gulf stock markets traded narrowly early on Tuesday as many investors stayed away with the approach of Eid al-Adha holidays beginning this week, but Qatar's bourse dropped after Fitch cut the country's credit rating.

Fitch lowered Qatar by one notch to AA-minus with a negative outlook on Monday, citing the impact of sanctions on Doha imposed by other Arab states. That brought Fitch into line with the other two major rating agencies, Moody's and Standard & Poor's.

The downgrade threatens higher funding costs for Qatari banks as they seek to replace deposits and loans that are being withdrawn by the other Arab states. Qatar National Bank fell 1.2 percent as Qatar's stock index lost 1.1 percent.

The most heavily traded stock, Qatar Gas Transport (Nakilat), dropped 2.3 percent to its lowest level since early July.

Saudi Arabia's index edged up 0.1 percent as industrial pipe maker Amiantit, the most heavily traded stock, jumped 5.3 percent after saying it expected a capital gain of 50-60 million riyals ($13.3-16.0 million) and positive cash flow of between 2 and 4 million riyals in the third quarter due to the merger of its European entities.

Development Works Food surged 10.3 percent after reoporting second-quarter net profit rose by almost two-thirds from a year earlier as revenues more than doubled.

In Dubai, the index edged down 0.1 percent although GFH Financial, the most active stock, gained 1.7 percent. Dana Gas retreated 1.5 percent in Abu Dhabi, helping pull the index there down 0.4 percent.

(Reporting by Andrew Torchia, editing by Louise Heavens) ((andrew.torchia@thomsonreuters.com)(+9715 6681 7277)(Reuters Messaging: andrew.torchia.thomsonreuters.com@reuters.net))