The United Arab Emirates hacked web sites in nearby Qatar, prompting the feud among several Gulf states that's nearly two months old with no sign of a resolution, The Washington Post reported.
The newspaper report, published online Sunday evening, cited unnamed U.S. intelligence officials. The story said the Emirates orchestrated the hacks, though it said it wasn't clear whether the UAE carried out the cyber attack on its own, or contracted another party to do it.
The Emirates denied the report.
"I just want to say that the Post story is completely untrue," the Emirates' minister of state for foreign affairs, Anwar Gargash, told the BBC.
The crisis erupted May 24, when Qatar's emir, Sheikh Tamim Bin Hamad al-Thani, was cited on government and news websites as praising Iran and the radical Palestinian group Hamas. Such statements are at odds with the prevailing sentiment in the Gulf.
Qatar said those reports were fabricated and posted by hackers, though it hasn't identified the source.
Still, four Arab states — the United Arab Emirates, Saudi Arabia, Egypt and Bahrain — cut diplomatic and trade ties with Qatar and issued a list of 13 demands.
The United States, which is allied with Qatar and its critics, has sought to broker a solution. Secretary of State Rex Tillerson shuttled around the region last week, but but returned home without a breakthrough.
While the statements attributed to Qatar's emir sparked the current crisis, Qatar has been at odds with the other conservative monarchies in the Gulf for many years.
They say Qatar has supported many radical groups. Qatar says this is part of it's open-door policy, and the aim is to encourage dialogue, not to give backing to extremists.
The Emirates' ambassador to the U.S., Yousef al-Otaiba, denied The Washington Post report, and then went on to say in a statement:
"What is true is Qatar's behavior. Funding, supporting, and enabling extremists from the Taliban to Hamas and Gadhafi. Inciting violence, encouraging radicalization, and undermining the stability of its neighbors."