DUBAI, Oct 25 (Reuters) - Credit ratings agency Fitch Ratings indicated on Monday it could cut the ratings of three banks in Qatar, saying it was concerned over the sector’s increasing reliance on external funding and a recent rapid growth in assets. Fitch placed Doha Bank, Al Khalij Commercial Bank and Qatar Islamic Bank on “ratings watch negative”, meaning it sees a greater potential for a downgrade in their ratings. The Qatari banks’ reliance on “external funding, coupled with the large size of the banking system, could have moderately weakened the authorities’ ability to support the banking sector,” the ratings agency said in a statement. (Reporting by Hadeel Al Sayegh; Editing by Kirsten Donovan)