France is mobilising 7,000 soldiers and increasing its alert status to "emergency attack" level after the death of a teacher in the northeast town of Arras, stabbed to death Friday by a former student with a record of Islamic radicalisation.

President Emmanuel Macron made the decision after convening an emergency meeting of his security cabinet on Friday night.

Macron has described the stabbing attack, which left two other staff members at the school seriously injured, as "Islamist terrorism."