Qatar's Ministry of Interior say experts now have evidence showing that the cyberattack on the country's official media originated from the United Arab Emirates.

During a news conference in Doha on Thursday, officials said the planning for the hacking of Qatar News Agency (QNA) started as early as April.

Investigators also reportedly traced the IP (internet protocol) address linked to the hacking to the UAE.

Speaking to Al Jazeera, Captain Othman Salem al-Hamoud said that the level and the quality of the hacking was so professional that it had to have "state resources" behind it.

READ MORE: UAE arranged hacking of Qatari media, says Washington Post

Earlier, Lieutenant-Colonel Ali Mohammed al-Mohannadi, head of the ministry's technology division, said the hacking operation took place in coordination with, and through, "one of the blockading states".

"The hackers had total control of the QNA network, including the related accounts, websites and related social platforms," Mohannadi said.

"This was meant to fabricate and post the false reports, which were attributed to His highness, the Emir."

Officials said the case has been referred to prosecutors.

Video presentation

The cyberattacks reportedly lasted for about three hours, from late at night on May 24 to the early hours of May 25, before the state media's IT experts managed to take back control of the site.

In a video presentation, the ministry said that investigators found out that as early as April, hackers had already "infiltrated" the QNA network "using VPN software" and "scanned the website".

The ministry said the hackers "exploited" a loophole in the network's system, and installed "malicious programmes" which were then later used to carry out the publishing of the "false stories".

Addresses, passwords and emails of all the employees of the state news agency were also collected.

An earlier report in the Washington Post said the UAE arranged the operation.

READ MORE: Qatar-Gulf crisis - All the latest updates

The US newspaper reported on Sunday that information from US intelligence officials showed that senior UAE government officials discussed the planned hacks on May 23, the day before the alleged hacking occurred.

The officials said it was unclear if the UAE hacked the websites or paid for them to be carried out, the newspaper reported.

The Washington Post did not identify the intelligence officials it spoke to for the report.

Yousef al-Otaiba, UAE ambassador to the US, rejected the report in a statement, saying it was "false".

Anwar Gargash, UAE state minister for foreign affairs, also said "the Washington Post story is not true, simply not true".

Al Jazeera's Ali Younes contributed to this report. Follow him on Twitter @Ali_reports