Isis has called on its supporters to “slaughter” Americans voting in the presidential election and urged that US Muslims do not take part in the “apostasy of democratic voting”.

A seven-page document released by its media centre, the group said in its standard tone “the blood of Crusader voters is even more deserving of being spilled than the blood of Crusader combatants”.

Isis called on its followers to tell US voters: “We have come to slaughter you and smash your ballot boxes." The essay concluded: “May Allah make this year’s US presidential election a dreadful calamity like no other to have struck America throughout its pathetic history.”

Isis 'teaching children how to kill and make bombs'

It comes as the FBI investigates reports suggesting a major terrorist attack was being planned.

Intelligence gathered by US authorities reportedly suggested al-Qaeda may be planning attacks in the states of New York, Texas and Virginia to coincide with the election. Reports in US media said authorities in the three states had been placed on alert.

The new Isis threats were published by Al Hayat, the group’s media outlet. They were reported by the SITE monitoring group, a US-based organisation that tracks terrorist communications.

The document, which was published in English, began by condemning recent US presidents and their foreign policies. It claimed Democrats and Republicans were the same in their “policies against Islam and Muslims” and raged against US interventions in the Middle East, support for Israel, drone strikes and the ongoing use of Guantanamo Bay.

The writers praised "the blessed September 11th operations” and condemned Muslims who supported former President George W Bush, suggesting they were responsible for him winning the presidency and therefore “share in the crimes committed by Bush against Islam and the Muslims”.

NYPD responds to terror threat 11/4/16 Show all 6 1 /6 NYPD responds to terror threat 11/4/16 NYPD responds to terror threat 11/4/16 Officers from the NYPD anti-terror unit patrol Times Square, Friday Nov. 4, 2016, in New York. The FBI and New York Police Department say they are assessing the credibility of information they received of a possible al-Qaida terror attack against the U.S. on the eve of Election Day. Officials say Friday that counterterrorism investigators are reviewing the information that mentioned New York, Texas and Virginia as potential targets. An NYPD spokesman says in a statement the information "lacks specificity. Bebeto Matthews/AP NYPD responds to terror threat 11/4/16 NYPD install police security camera near the Hilton hotel in New York, Friday Nov. 4, 2016, where Donald Trump organizers will gather on election night. The FBI and New York Police Department say they are assessing the credibility of information they received of a possible al-Qaida terror attack against the U.S. on the eve of Election Day. Officials say Friday that counterterrorism investigators are reviewing the information that mentioned New York, Texas and Virginia as potential targets. An NYPD spokesman says in a statement the information "lacks specificity." Bebeto Matthews/AP NYPD responds to terror threat 11/4/16 NYPD install police security camera near the Hilton hotel in New York, Friday Nov. 4, 2016, where Donald Trump organizers will gather on election night. The FBI and New York Police Department say they are assessing the credibility of information they received of a possible al-Qaida terror attack against the U.S. on the eve of Election Day. Officials say Friday that counterterrorism investigators are reviewing the information that mentioned New York, Texas and Virginia as potential targets. An NYPD spokesman says in a statement the information "lacks specificity." Bebeto Matthews/AP NYPD responds to terror threat 11/4/16 NYPD install police security camera near the Hilton hotel in New York, Friday Nov. 4, 2016, where Donald Trump organizers will gather on election night. The FBI and New York Police Department say they are assessing the credibility of information they received of a possible al-Qaida terror attack against the U.S. on the eve of Election Day. Officials say Friday that counterterrorism investigators are reviewing the information that mentioned New York, Texas and Virginia as potential targets. An NYPD spokesman says in a statement the information "lacks specificity." Bebeto Matthews/AP NYPD responds to terror threat 11/4/16 Officers from the NYPD anti-terror unit patrol Times Square, Friday Nov. 4, 2016, in New York. The FBI and New York Police Department say they are assessing the credibility of information they received of a possible al-Qaida terror attack against the U.S. on the eve of Election Day. Officials say Friday that counterterrorism investigators are reviewing the information that mentioned New York, Texas and Virginia as potential targets. An NYPD spokesman says in a statement the information "lacks specificity." Bebeto Matthews/AP NYPD responds to terror threat 11/4/16 Officers from the NYPD anti-terror unit patrol Times Square, Friday Nov. 4, 2016, in New York. The FBI and New York Police Department say they are assessing the credibility of information they received of a possible al-Qaida terror attack against the U.S. on the eve of Election Day. Officials say Friday that counterterrorism investigators are reviewing the information that mentioned New York, Texas and Virginia as potential targets. An NYPD spokesman says in a statement the information "lacks specificity." Bebeto Matthews/AP

In discussing the current presidential candidates, the group wrote: “The only differences between Trump and Clinton are that Clinton is more skilled in ‘political correctness’, that she is a female feminist – and the Prophet said ‘Never shall a people who give their leadership to a woman be successful' – and that Trump is impulsive and unpredictable."

They said Mr Trump was “yet to learn that what he refers to as ‘radical Islamic terrorist’ is nothing but the teachings of Islam, plain and simple”.

The essay invoked numerous religious arguments and quoted from Islamic scriptures in an attempt to persuade followers that voting in “the pagan festivals of US democracy” was a sin.

The document, titled “The Murtadd [Apostate] Vote” contained images of Donald Trump, which it said was “courting Jews”; Hillary Clinton’s running mate Tim Kaine meeting Israeli Prime Minister Benjamin Netanyahu; and Khizr Khan, the father of a Muslim US soldier killed in combat, who delivered a powerful speech in support of Ms Clinton at the Democratic convention in July.

The militant group believes the only legitimate law is the word of Allah, and that democracy is a sin because it results in a national law that is separate to Islamic sharia teachings.

Therefore “one who votes in the democratic system is an apostate”, Isis said.

Isis was founded in 2014 and has since gained control of large swathes of land in Syria and Iraq.

However, it is now in retreat across much of its territory, with a Western-backed coalition of forces attacking it in northern Iraq and Syria.