A leaked classified document contains a warning by US Secretary of State Hillary Clinton that Saudi Arabian donors were the most significant source of funding to Sunni terrorist groups worldwide.
The groups funded include al-Qaeda, the Taliban and Lashkar-e-Taiba, she added.
The BBC reports that in the memo, released by WikiLeaks, Mrs Clinton said it was an ongoing challenge to persuade Saudi officials to treat such activity as a strategic priority.
In one classified cable sent in December 2009, Mrs Clinton urged diplomats to redouble efforts to stop funds reaching militants "threatening stability in Pakistan and Afghanistan and targeting Coalition soldiers".
The document also criticised efforts to combat militants by the UAE, Qatar and Kuwait.
