Investigators have revealed the foiled Dusseldorf terror attack was directed by Islamic State and the Syrian attackers were much further along in their plans than previously thought.

In June of last year, several Syrian asylum seekers were caught planning a terrorist attack in the old town area of Dusseldorf. The Federal Court of Justice (BGH) has revealed, after months of investigation, the Syrians were under orders from Islamic State and their plans were quite advanced, Die Welt reports.

The BGH report states, “The planning of the act was already well advanced” and noted that the attack was planned for a weekend “because the Old Town of Düsseldorf is regularly particularly lively on these days”.

The methodology of the attack is said to be similar to the 2015 Paris attack which saw Islamic State terrorists employ a mix of suicide bombers and fighters armed with automatic rifles. The report states two of the Syrians would blow themselves up in the chaos and a further two would use automatic Kalashnikov rifles.

“They should shoot as many escaping people as possible and after the emptying of their magazines finally blow themselves up,” the report states.

One of the Syrians had betrayed the terror cell and that led police to arrest the remaining members. Authorities said that the information he gave was met with suspicion but was confirmed later after looking at several Facebook accounts of members of the cell.

The order to carry out the attack is largely believed to have come directly from Islamic State at the beginning of June, much like the terror attack at the Berlin Christmas market in December which is said to have also been ordered by Islamic State.

29-year-old Saleh A. is said to have been the main contact with Islamic State and is said to have received orders from the terror group who are based in Raqqa in Syria. A German-born Islamic State sympathiser is also said to have also helped by sketching a map of the area for the terror suspect.

Salah A. arrived as an asylum seeker in Germany in March of 2015 and in February of 2016 he met with a man named Abd Arahman A.K. who was supposed to manufacture bullet proof vests for the cell and aid them with the transportation of explosives.

The investigation is still ongoing and the BGH has yet to look at the mobile phones of three of the suspects which could present further evidence. Currently, the authorities are working with governments in Belgium, France, the Netherlands, Turkey, and Algeria to examine the connections of the Syrians and may possibly request help from Jordan and the United States.