Accusations that Iran plotted to have former President Trump killed are "unsubstantiated and malicious," Iran's Permanent Mission to the United Nations told Fox News Digital.

Authorities received intelligence in recent weeks from a human source regarding an Iranian plot to kill Trump, which prompted an increase in U.S. Secret Service protection, federal law enforcement sources told Fox News. 

The plot doesn't appear to be connected to Thomas Matthew Crooks, 20, the gunman who shot Trump during his campaign rally in Butler, Pennsylvania, over the weekend, the sources said. 

The Secret Service increased its protection detail assigned to Trump because of the intelligence. The agency had grown concerned about the former president holding outdoor events and expressed its concerns to the Trump campaign. 

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Donald Trump gestures with a bloodied face as multiple shots rang out during a campaign rally

Former President Trump gestures with a bloodied face after shots rang out during a campaign rally Saturday in Butler, Pennsylvania. (Reuters/Brendan McDermid)

"The Secret Service and other agencies are constantly receiving new potential threat information and taking action to adjust resources, as needed," Secret Service chief of communication Anthony Guglielmi said in a statement to Fox News Digital. "We cannot comment on any specific threat stream other than to say that the Secret Service takes threats seriously and responds accordingly."

Fox News Digital has reached out to the Trump campaign and the Department of Homeland Security.

Iran's Permanent Mission to the United Nations said the allegations were untrue. 

"From the perspective of the Islamic Republic of Iran, Trump is a criminal who must be prosecuted and punished in a court of law for ordering the assassination of General Soleimani. Iran has chosen the legal path to bring him to justice," it said in a statement. 

Trump has been an increasing target for Iran following the January 2020 killing of Lt. Gen. Qassem Soleimani, the leader of Iran's Islamic Revolutionary Guard Corps Quds Forces.

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Iran flag burning

Iranians burn American flags during an anti-U.S. demonstration outside the former U.S. embassy headquarters in Tehran in 2018. (Ali Mohammadi/Bloomberg via Getty Images)

Soleimani was killed in a Jan. 3, 2020, U.S. strike in Baghdad, days after Iranian-backed militia supporters stormed the U.S. Embassy in Iraq. 

"It would be a historic mistake to pretend the IRGC does not mean what they say... Supreme Leader Khamenei harbors personal hatred for Trump due to Trump's historic decision to target Iran's chief terrorist, Qassem Soleimani, in Iraq in 2020," said Behnam Ben Taleblu, a Foundation for Defense of Democracies expert on Iran's global threat network.

News of the alleged threat came as Iran's acting foreign minister, Ali Bagheri Kani, is slated to visit New York this week for meetings at the United Nations.

Qassem Soleimani

Iranian terror leader Gen. Qassem Soleimani (AP)

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"The U.S. government should deny a visa to Iran’s regime’s Acting Foreign Minister Ali Bagheri Kani," said United Against Nuclear Iran CEO Ambassador Mark D. Wallace. "He is visiting New York as Tehran plots assassination and kidnapping attempts against Americans on U.S. soil."

"When Iranian officials have visited the United States in the past, a delegation of individuals have accompanied them who have troubling ties to the Islamic Revolutionary Guard Corps (IRGC), which is spearheading these operations against Americans," he added.