GETTY Tourists are being warned of the danger of ISIS attacks at Christmas markets

FREE now and never miss the top politics stories again. SUBSCRIBE Invalid email Sign up fornow and never miss the top politics stories again. We will use your email address only for sending you newsletters. Please see our Privacy Notice for details of your data protection rights.

Officials say Islamic State is also planning to attack churches over the Christian holiday season warning visitors to be careful of visiting "places of worship." Winter-time markets are popular in France, Germany, the UK, Austria, Switzerland and attract millions of people each year. And millions will attend Christian services all over the continent on the run up to Christmas day. However, US intelligence services are warning there is a high risk of attack from Islamic terrorists determined to continue their reign of terror this year.

GETTY Christmas markets are on high alert as credible threats have been detected

In an unprecedented release the US has warned all citizens to be on their guard if travelling to Europe. They say: "Credible information indicates the Islamic State of Iraq and the Levant (ISIL or Da'esh), al-Qa'ida, and their affiliates continue to plan terrorist attacks in Europe, with a focus on the upcoming holiday season and associated events. "US citizens should also be alert to the possibility that extremist sympathisers or self-radicalised extremists may conduct attacks during this period with little or no warning.

GETTY Christmas markets are a target for ISIS operatives

"Terrorists may employ a wide variety of tactics, using both conventional and non-conventional weapons and targeting both official and private interests. "US citizens should exercise vigilance when attending large holiday events, visiting tourist sites, using public transportation, and frequenting places of worship, restaurants, hotels, etc. "Be aware of immediate surroundings and avoid large crowds, when possible. "Review security information from local officials, who are responsible for the safety and security of all visitors to their host country."

Paris Terror Attack 2015: One year on Sun, November 13, 2016 Terrorists slaughtered 130 people during a series of coordinated terror attacks in Paris on Friday 13th November 2015. The attacks took place at the Bataclan concert hall, Boulevard Voltaire, Belle Equipe bar, rue Fontaine au Roi, Petit Cambodge restaurant, and Le Carillon bar. Play slideshow REUTERS 1 of 86 French President Francois Hollande and Paris Mayor Anne Hidalgo lay a wreath of flowers as they unveil a commemorative plaque next to the