The Green party leader, Zack Polanski, thoughtlessly undermined the confidence of officers to deal with dangerous people by sharing a critical social media post after the Golders Green stabbings, according to the head of the Metropolitan police.

Officers were filmed detaining the suspect after two Jewish people were stabbed in the north-west London suburb on Wednesday.

Polanski retweeted, without comment, a post on X alleging that officers “repeatedly and violently kicking a mentally ill man in the head” when he was already incapacitated by a stun gun.

In a letter to Polanski , the Met commissioner, Mark Rowley, described the claim as “inaccurate and misinformed commentary”.…