Qatar has called the alleged hacking of its state news agency by the United Arab Emirates (UAE) “a violation of international law”.

Reports surfaced in the Washington Post on Sunday claiming that government officials in Abu Dhabi orchestrated the planting of a fabricated story in Qatari media on 24 May that contributed to the current political spat in the region.

Qatari Emir Tamim bin Hamad Al Thani was falsely quoted as praising Hamas and Hezbollah, as well as speaking positively about Iran and Israel – remarks that drew the ire of Saudi Arabia and the UAE, and were later used as justification for severing diplomatic ties with the tiny Gulf kingdom.

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“The information published in The Washington Post ... revealed the involvement of the United Arab Emirates and senior Emirati officials in the hacking of Qatar News Agency,” the Doha government’s communication office said in a statement on Monday.

The report “unequivocally proves that this hacking crime took place”, it added.

Earlier on Monday, the UAE’s foreign minister Anwar Gargash told an audience at London think tank Chatham House there was no truth to the allegations made by both Qatar and The Washington Post, which cited information newly analysed by US intelligence services.

It is understood the FBI has been assisting Qatar with an investigation into the hack for several weeks.

The story quotes unnamed US sources who believe senior UAE government officials had discussed the planned hacks of the news agency and government social media accounts on 23 May – the day before they occurred.

US President Donald Trump visited the region the next day, meeting with Gulf leaders in Riyadh, and the operation was put into action later the same day.

Saudi Arabia cuts ties with Qatar over terror links

It was not clear whether the UAE hacked the Qatari sites itself or paid another entity to do so, The Post added.

The false remarks by Emir Al Thani were quickly picked up and circulated by other Gulf news outlets, even after Qatar issued a statement clarifying the story was fabricated. Officials in Doha said the bad faith with which their assurances were received showed evidence of foul play at the time.

Riyadh, Abu Dhabi and allies in Egypt and Bahrain cut trade and political ties with Qatar on 5 June, claiming that Doha meddled in international affairs and funded terrorist organisations. Qatari officials have vehemently denied the claims.

The five-week-old standoff has led to economic chaos, split up families, stranded migrant workers and led to US worries about the impact on coalition counter-terrorism efforts against Isis. All talks aimed at de-escalating the crisis have so far proven inconclusive.

A US State Department spokesperson said on Secretary of State Rex Tillerson’s return from the region over the weekend that no party was expecting a “near-term resolution” to the row.