British intelligence officials reportedly believe that the hack that compromised about 100 email accounts relating to members of the country's parliament and Prime Minister Theresa May Theresa Mary MayAre US-Japan relations on the rocks? Trump insulted UK's May, called Germany's Merkel 'stupid' in calls: report Bolton says Boris Johnson is 'playing Trump like a fiddle' MORE was perpetrated by hackers linked to Iran.

The Times newspaper reported Saturday that a "sustained attack" in June that affected 9,000 email accounts and breached about 100 was linked to Tehran, marking Iran's first significant cyberattack on the U.K.

According to intelligence officials, the cyberattack “bombarded parliamentary email accounts” but only compromised about 1 percent of the accounts it affected. The attack was initially thought to be the result of amateur hackers and not a nation-state.

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“Whitehall officials admitted it was inevitable that the hackers had obtained sensitive material," the Times reported.

News of the attack's culprit comes just a day after President Trump announced he would decertify the Iran nuclear deal while stopping short of pulling out of the Obama-era accord.

May, along with German Chancellor Angela Merkel and French President Emmanuel Macron, issued a joint statement Friday night calling the deal "the culmination of 13 years of diplomacy."

In a speech at the White House, Trump accused Iran of violating the "spirit" of the deal and said the U.S. would not "take lightly" the country's "sinister vision for the future."

“I am announcing today that we cannot and will not make this certification,” Trump said.

“We will not continue down a path whose predictable conclusion is more violence, more terror and the very real threat of Iran’s nuclear breakout," he continued.