The United Arab Emirates ambassador to the United States, Yousef al-Otaiba, berated Saudi Arabia's leadership, a series of emails leaked by a computer hacking group reveal.

In a 2008 email chain with his wife Abeer Shoukry, published by the Middle East Eye news website on Friday, Otaiba described the kingdom's leaders as "f****ing coo coo".

"Global Leaks" leaked the correspondence; the company is not to be confused with the Milan-based software company GlobalLeaks.

Otaiba's profane message is in reference to a decision by the Saudi government in 2008 to ban the sale of red roses on Valentine's Day.

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The emails reflect a plan by Abu Dhabi to paint Saudi Arabia as a dysfunctional and religiously conservative country, whose best hope for reform was Mohammed bin Salman, the newly appointed crown prince.

The correspondence makes a case for bin Salman over his cousin and former crown prince, Mohammed bin Nayef.

Influencing the 'Saudi throne'

One document from Otaiba revealed that it was time for the Emiratis to get "the most results we can ever get out of Saudi".

Another email to New York Times columnist Tom Friedman said that the UAE saw bin Salman as a favourable change within Saudi Arabia.

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An exchange with David Petraeus, former CIA director and commander of coalition forces in Iraq, saw Otaiba suggest that bin Salman is more engaged in day-to-day issues, while dismissing the man he later replaced, Mohammed bin Nayef, as being "off his game".

In a major reshuffle in late June, Saudi Arabia's King Salman appointed his son, bin Salman, as his heir, removing his nephew bin Nayef.

David Hearst, Middle East Eye editor and author of the article, said UAE leaders see the current crown prince, bin Salman, as "their man" in Riyadh.

"Because bin Nayef had a very good record and a very good reputation in Washington, one of the aims was to sow the seeds of doubt," he told Al Jazeera from London.

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He explained that Abu Dhabi was attempting to make opportunity of a US retreat from the Middle East and influence "the Saudi throne"

"That is incidentally why Otaiba spent so much trouble putting the knife in bin Nayef for quite sometime before he actually got sacked as the crown prince," Hearst said.

'Washington's charming man'

Otaiba is a well-known figure in US national security circles, described by some as "the most charming man in Washington".

He has participated in Pentagon strategy meetings at the invitation of defence officials.

The latest leak comes after hackers released the first series of emails from the inbox of the UAE envoy in early June.

Those emails showed that the Emirati ambassador played a role in a campaign to downgrade the image and importance of Qatar as a regional and global power.

The emails also showed collusion with journalists who have published articles accusing Qatar and Kuwait of supporting "terrorism".

The release of those leaked emails came a week after a cyberattack on Qatar's official news agency, during which fake remarks critical of US foreign policy were posted and attributed to the Qatari emir.

Two days after the initial release of emails, Saudi Arabia, Bahrain, UAE and Egypt cut all diplomatic and trade ties with Qatar for supporting "terrorism". Qatar denies the allegations.