Authorities in Barcelona have been placed on high alert after receiving information on a potential planned terror attack and began a search for a Moroccan migrant believed to be connected to the threat.

The initial terror warning was made public by the U.S. State Department which wrote on social media, “Spain: Exercise heightened caution around areas of vehicle movement, including buses, in the Las Ramblas area of Barcelona during Christmas and New Year’s.

“Terrorists may attack with little or no warning, targeting tourist locations, transportation hubs, and other public areas.”

Catalonian Interior Minister Miquel Buch told local radio Rac1 that the regional police, the Mossos d’Esquadra, along with other Spanish police forces were cooperating to investigate the threat.

#Spain: Exercise heightened caution around areas of vehicle movement, including buses, in the Las Ramblas area of Barcelona during Christmas and New Year’s. Terrorists may attack with little or no warning, targeting tourist locations, transportation hubs, and other public areas. pic.twitter.com/MPGiZwMwxq — Travel – State Dept (@TravelGov) December 23, 2018

Spanish media also reported that investigators had begun a manhunt to locate a 30-year-old man from Casablanca, Morocco, identified only as “B.L.” by El Pais, who is wanted in connection to the threat.

The English language version of the newspaper reports that the migrant has a bus driver’s licence and he has a previous police record in Spain for insulting a Civil Guard officer at Málaga airport in 2006.

Local newspaper El Periodico de Catalunya has claimed that internal police documents show that authorities fear the possibility of a terrorist hijacking a bus in Barcelona and using it to commit a terrorist attack, likely in the same style as the Berlin Christmas market attack that saw a dozen killed in 2016.

Last year, Barcelona and the nearby resort town of Cambrils were targetted by Islamic State in a double attack that led to the deaths of 16 people and eight terrorists.

LATEST: Spanish media reports 'several dead', 'hostages' taken by killers in Barcelona terror attack https://t.co/lLrXBAfYTv — Breitbart London (@BreitbartLondon) August 17, 2017

It was later revealed that the terrorists had also plotted attacks against other targets including the Eiffel Tower in Paris where they planned on setting off a large truck bomb at the base of the structure.

The main attacker, Younes Abouyaaqoub, along with other members of the terror cell who were killed by police, were all Moroccan in origin. Migrants, particularly failed asylum seekers, have been involved in several high-profile terror attacks including the Stockholm terror attack and the Berlin Christmas market attack.

Around half of the terror plots in Germany have involved asylum seekers, according to findings from the U.S. Heritage Foundation think tank.