Terrorist group ISIS have threatened to behead football stars Lionel Messi and Cristiano Ronaldo ahead of the 2018 FIFA World Cup in Russia.

This isn't the first piece of propaganda that the fundamentalist group has made regarding the World Cup, but this latest threat shows pictures of the pair - widely regarded as the world's best footballers - laid out on the pitch of a stadium as ISIS soldiers cut their heads off.

The text on the sickening picture reads: "The ground will be filled with your blood".

The group is losing territory in Syria and Iraq but has made calls to 'lone attackers' based in Russia to launch attacks on the tournament that gets underway in June.

They released a second poster that shows an ISIS fighter holding what appears to be a grenade inside a stadium. This poster is captioned: "FIFA World Cup Russia 2018. Victory will be ours."

Messi has been used before in their horrible campaigns. Earlier this year they posted a picture of him mocked up in an orange jumpsuit similar to those worn by detainees in Guantanamo Bay and other hostages that have been beheaded by ISIS on camera.

He was pictured in Moscow's Luzhniki Stadium, which will host the World Cup final this year, and the writing above him read: "So strike them upon the necks and strike them from every fingertip."

Last October another poster showed the Barcelona forward in a jail cell with a bloodied face. This time the writing said: "I swear that the Mujahideen's fire will burn you...just you wait."

The World Cup will take place between 14 June and 15 July, 2018, and matches are scheduled to take place across 11 cities in the country.

One of the cities in which matches will be played is St Petersburg which suffered a terrorist attack back in April 2017 when a suicide bomber detonated explosives on the city's underground train system.

The attack was claimed by ISIS as a response to Russian air strikes against them in Syria.

Thousands of England fans are thought to be basing themselves in the city for the duration of the tournament.

Russia has a high number of people that have travelled to ISIS controlled areas to be trained as militants. As many as 2,400 people, mainly from areas of Russia within Central Asia, are thought to have travelled to the Middle East to fight for ISIS.