Harry Sarfo, who was born in Germany but raised in the UK, said Isis commanders want to carry out multiple attacks in Europe.
He told the New York Times that when he arrived in Syria in 2015 he was told to return to his home in Bremen, Germany to plot a terror attack.
The 27-year-old described an encounter with masked members of Isis’s secret service, who told him and a German friend they needed to go home.
He said: “He was speaking openly about the situation, saying that they have loads of people living in European countries and waiting for commands to attack the European people.
“And that was before the Brussels attacks, before the Paris attacks.”
“They said, ‘Would you mind to go back to Germany, because that’s what we need at the moment’.
“And they always said they wanted to have something that is occurring in the same time: They want to have loads of attacks at the same time in England and Germany and France.”
Sarfo, who is currently serving a prison sentence in Germany for terror offences, said there had been many recruits in the UK and Germany, but they had “chickened out” before carrying out attacks.
But in contrast, they had more than enough volunteers for terrorist attacks in France.
He said when his friend asked about French recruits, the Isis commanders had started laughing and said “don’t worry about France”.
The former postman said hundreds of militants had “definitely” returned to Europe.