BEIRUT (AFP) - An ISIS "soldier" carried out the wave of stabbings at a mall in the US state of Minnesota that wounded nine people, an extremist-linked news agency said Sunday.

"The executor of the stabbing attacks in Minnesota yesterday (Saturday) was a soldier of the Islamic State who carried out the operation in response to calls to target citizens of countries belonging to the crusader coalition," Amaq news agency said.

ISIS (Islamic State in Iraq and Syria) has repeatedly called for lone-wolf attacks on countries in the US-led coalition targeting the extremist group with air strikes in Syria and Iraq, with France and Belgium bearing the brunt of such actions.

US police said an off-duty officer shot dead a suspect who had stabbed and wounded eight people in a shopping mall in Minnesota on Saturday night.

He "made some references to Allah", said Blair Anderson, police chief in the city of St. Cloud, and "asked at least one person if they were Muslim before he assaulted them."

The motivation remained unclear, Anderson stressed to journalists.

"Whether that was a terrorist attack or not, I'm not willing to say that right now because we just don't know." Anderson said the assailant at the Crossroads Centre mall in St Cloud, some 110 kilometres northwest of Minneapolis city, was wearing a private security uniform.

The suspect had a history of minor traffic violations, he said, adding that police did not currently have reason to believe the attack was connected to any other incident.

The stabbings came as 29 people were wounded in a bomb attack on a busy New York neighbourhood Saturday.