Hapless Islamic State militants have vowed online to take over Rome - and 'throw homosexuals off the leaning tower of pizza'.

In the message, posted by a Twitter account linked to the terror group, the ISIS supporter also threatens to bring sharia law to the Italian capital.

It comes just days after masked jihadists warned of their intention to conquer the city in a video that showed the mass beheading of 21 Christians in Libya.

But rather than spark widespread panic, the threats have triggered a flood of mocking responses - with dozens taking to social media to make fun of the jihadists and their takeover plans.

Hapless: Above, the tweets posted today by an account linked to the Islamic State. In them, the user threatens to bring shariah law to Rome and 'use your leaning tower of pizza to throw off homosexual'

In the threat posted today, Twitter user Abu Abdullah Britani, who openly publicises ISIS activity, wrote: '#We_Are_Coming_O_Rome with slaughter'.

The message was soon followed by one that read: '#We_Are_Coming_O_Rome, we will conquer & establish the justice of #shariah. We will use your leaning tower of pizza to throw off homosexual'.

The terrorists have previously thrown men off of buildings for 'being gay'.

Earlier this year, images emerged that appeared to show militants hurling one man off a building in the town of Tal Abyad in Raqqa as supposed punishment for having a ‘homosexual affair’.

This most recent threat appears to indicate the terrorists intend to bring their barbaric practices to Europe - and plan to repeat the horrific scenes off the Leaning Tower of Pisa.

It appears the tweeter is unaware the tower is in Pisa, not Rome.

The hashtag #We_Are_Coming_O_Rome has been used by Islamic State supporters to discuss plans to reach Rome after the city was mentioned in a sickening video released earlier this week.

Sickening: The threats come just days after masked ISIS jihadists warned of their intention to conquer the city in a video that showed the mass beheading of 21 Christians in Libya. Above, a still from the brutal clip

The footage, which lasts five minutes, shows the Egyptian Christians dressed in jumpsuits being marched one by one along a lonely beach, each held by a fighter clad in black.

The captives, their faces uncovered, are made to kneel before being forced to lie down. The masked jihadists then behead them simultaneously.

In the video, one of the militants warned: 'Today we are south of Rome. We will conquer Rome with Allah’s permission.'

They claimed their prisoners had been beheaded in Libya - just 220 miles south of Italy.

In the wake of the threat, Italian security chiefs have approved plans to put 4,800 soldiers on the country's streets and post them to 'sensitive sites' to help prevent terrorist attacks.

Response: Rather than spark widespread panic, the threats have triggered a flood of mocking responses - with dozens taking to social media to make fun of the jihadists and their takeover plans

Reports claim 500 will be deployed in Rome - where soldiers are already guarding diplomatic residences, synagogues and Jewish schools.

The troops are also expected to be deployed at tourist venues such as archaeological sites and monuments.

Meanwhile, the commander of Vatican City's 110-man Swiss Guard said his forces are ready to defend Pope Francis if ISIS attempt a strike .

But some experts have claimed that 'Rome' could be being used as a symbolic term by the terrorists, and might refer to the United States, Turkey, or the West as a whole.

Mocking: Some Romans offered advice to ISIS - with some warning them against travelling in rush-hour traffic (top) and another pointing out that the city already has a list of problems to address (above)

Unconvinced Twitter users have taken to the social networking site to undermine ISIS threats with a number of tweets and mocking memes.

Some played on the city's history as the home of fearsome warriors, with one user posting an image of Russell Crowe in Gladiator with the message 'So you are coming to Rome, let me entertain you'.

Another posted a cartoon of men dressed in armour and shields with the caption 'Italian special units alerted to the threat of ISIS...'

A number of Romans took the opportunity to offer advice to ISIS - with some warning them against travelling in rush-hour traffic and others pointing out there may be glass on the street.