US intelligence agencies confirmed in May that the UAE government discussed a plan to breach Qatar government websites, according to the Post.
Reacting to the Washington Post story, the UAE ambassador, Yousef al-Otaiba, claimed it was "false".
Sameh Shoukry, Egypt's foreign minister, said during a meeting with his Kuwaiti counterpart Sheikh Sabah al-Khalid al-Sabah in Cairo on Monday that the only way to resolve the Gulf crisis was for Qatar to comply.
The Washington Post cited U.S. intelligence officials as saying the UAE had orchestrated the posting of incendiary quotes attributed to Qatar's emir that he insisted were fabricated.
According to the official agency, Gargash said in a speech at the Royal Institute of International Studies in London, during a lecture entitled "The Gulf Crisis: its Causes and What will Lead", which dealt with the crisis with Qatar, including its background, consequences and prospects. The officials said it isn't clear whether the UAE carried out the hack itself or got someone else to do it.
"The UAE had no role whatsoever in the alleged hacking described in the article", the statement said according to the Washington Post.
The four countries, accusing Doha of supporting "extremism and terrorism", meddling in their internal affairs and cosying up to their rival Iran, have also imposed a sweeping air, sea and land blockade.
The main problem with Qatar is its alliance with extremist ideology and its spending of billions of dollars to support individuals and terrorist organizations, UAE News Agency WAM reported on Monday. "Inciting violence, encouraging radicalisation, and undermining the stability of its neighbors", the statement said.
The Federal Bureau of Investigation was previously known to be working with Qatar to probe the hacking.
At this time, Arab nations have not shown any signs of rekindling relationships with Qatar.