UAE rejects allegations of hacking Qatari news agency
Gargash said Qatar's neighbours were prepared to continue the boycott for months.
The UAE has denied that it was responsible for an alleged hacking of the Qatari state news agency and websites earlier this year.
Speaking at the Chatham House forum in London on Monday, UAE Minister of State for Foreign Affairs Dr Anwar Gargash questioned the veracity of the claims.
He said: "The Washington Post story is not true. It is purely wrong. You will see in the next few days the story will die." He denied the hack could have precipitated the crisis, saying "this issue has been festering since 2014".
The Post gave no further details of how American intelligence had reached its conclusion.
US intelligence agencies declined to comment on the Post's article, but the UAE's ambassador insisted that it "had no role whatsoever in the alleged hacking".
"What is true is Qatar's behaviour. Funding, supporting, and enabling extremists from the Taleban to Hamas and Gaddafi. Inciting violence, encouraging radicalisation, and undermining the stability of its neighbours," Yousef Al Otaiba wrote in a statement posted on Twitter.
The Guardian reported last month that an investigation by the US Federal Bureau of Investigation had concluded that freelance Russian hackers were responsible.
Gargash told the BBC that the UAE and five other Arab nations had not written to Fifa to demand that Qatar be stripped of the right to host the 2022 World Cup. He said the UAE would not escalate its boycott by asking companies to choose between doing business with it or Qatar.
Gargash told the BBC that Qatar's denial had been contradicted by its agreement to review a list of 59 individuals and 12 organisations who the UAE has accused of supporting terrorism and wants arrested or expelled.
"What we know now is that Qatar is admitting that the list is worthy, that the list needs to be looked at, and that they need to change some of their laws to ensure that there is a proper process to cover this list," he said.
Gargash said Qatar's neighbours were prepared to continue the boycott for months if it did not comply with the list of demands it was handed last month and agree to international monitoring.
"I understand the concern of our allies," he added. "But the issue is that we are being hurt, and the world is being hurt, by a state that has $300bn (£230bn) and is the main sponsor of this jihadist agenda."
"This is our message: You cannot be part of a regional organisation dedicated to strengthening mutual security and furthering mutual interest and at the same time undermine that security," he said.
"You cannot be both our friend and a friend of Al-Qaeda," he added.
The four countries - the UAE, Saudi Arabia, Egypt and Bahrain - imposed sanctions on Qatar on June 5, cutting diplomatic and transport ties with it, after accusing Doha of financing militant groups. Doha denied the accusations.
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