The US Federal Bureau of Investigation (FBI) has announced a probe into claims by the presidential campaign of Donald Trump that its internal communications were hacked by Iran.

The FBI released a brief statement reading: "We can confirm the FBI is investigating this matter."

Tehran has denied hacking the campaign of the former president.

What do we know about the hacking incident?

Trump had said on Saturday that Microsoft had informed his campaign that Iran had hacked one of its websites, adding the hackers were only "able to get publicly available information."

The campaign gave no specific evidence of Tehran's involvement.

This came after a Microsoft report on Friday which detailed attempts to interfere in the US 2024 presidential campaign by foreign agents.

It particularly cited an Iranian military intelligence unit in June sending "a spear-phishing email to a high-ranking official of a presidential campaign from a compromised email account of a former senior advisor" which it had taken over.

Microsoft gave no further details on the targets' identities.

Mounting accusations on Iran targeting Trump

The latest accusations come as a Pakistani man with alleged ties to Iran has been charged with a plot to carry out political assassinations in the US, reportedly against Trump.

Trump had testy relations with Iran during his four years in office, and any second term could be equally fraught.

The former president pulled out of a landmark 2015 deal that saw Tehran agree to curb its nuclear ambitions in return for an easing of Western sanctions. Instead, Trump reimposed sanctions, banning trade between the US and Iran.

Under Trump, the US killed Iranian military commander Qassem Soleimani in a drone strike on Iraq in January 2020.

Soleimani was considered second only to Iran's Supreme Leader Ali Khamenei as the most powerful person in Iran.

His assassination is believed to have prompted the political assassination plots which the Pakistani man is facing charges over.

rmt/jsi (AP, Reuters)