A 23-year-old man from Strasbourg, eastern France, has been identified as the third attacker involved in the terrorist assault at the Bataclan music hall in Paris, police sources have said.

Foued Mohamed Aggad went to Syria with his brother and a group of friends at the end of 2013, according to a source close to the investigation. Most of the others were arrested in spring last year after returning to France but Aggad stayed on in Syria, the source said.

The news was further confirmation that the deadly Paris attacks were carried out largely, if not entirely, by Europeans trained by Isis in Syria.

Ninety people died in the Bataclan attacks on 13 November, the single highest death toll in attacks in the city that night that killed 130. The two other Bataclan attackers have been identified as Omar Ismaïl Mostefai, 29, and Samy Amimour, 28.

Aggad was identified at the end of last week after his DNA was matched with those of his family members, the police source said.

The French prime minister, Manuel Valls, confirmed on BFMTV that the man had finally been identified. “What is important is that the investigation is progressing, that the accomplices are found out, that arrests happen,” he said.

“This will all take time and in the face of the terrorist threat that is unfortunately here, we need to carry on with this work of tracking down terrorists because we are at war with Daesh,” he said, using an Arabic acronym for Isis, which claimed responsibility for the attacks; Guardian reported.

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