A New York primary teacher allegedly organised a frenzied attack on her headteacher for sacking her friends.

The attack last September left Wanda Rivera-Switalski, 53, needing 150 stitches after she was slashed in the face by a masked knife-wielding motorcyclist as she left home for school .

Maths teacher Frances Levine was arrested late last month, a day before she was due to be promoted to assistant head at another school. Police also arrested Robert Somerville, who is accused of carrying out the attack on Ms Levine’s behalf. No money changed hands, but “she arranged it”, said police detective Kevin Czartoryski.

The pair, who were allegedly friends, have both been charged with attempted murder, assault and conspiracy. If convicted, they face up to 25 years in prison.

Ms Levine was overheard by a witness plotting the attack. It is alleged that she told Mr Somerville: “When are you going to do it? She already has fired three of my friends. Quit procrastinating.”

Ms Levine feared that she was next in line for the sack, said Richard Brown, district attorney for New York’s Queens district.

“The defendants conspired to attack the victim because of a belief by the teacher that her principal was about to take disciplinary action against her,” Mr Brown said in a statement.

Calls from Ms Levine’s mobile phone to her home number before and after the attack were traced to near the crime scene.

Ms Rivera-Switalski was approached by a helmeted man on a motorbike outside her home just before 8am on September 15. The attacker asked her name, before slashing her with a box-cutter and speeding off.

She has not returned to Public School 190 in east New York. Ms Levine continued to work there until her arrest on January 20.

Last week, an award-winning Michigan primary teacher was sentenced to life in prison without parole for the axe murder of her husband, despite pleas that she was a battered wife acting in self-defence.

Nancy Seam turned up for class the next day but police caught up with her after she was spotted on CCTV buying the weapon from a hardware store and officers saw “something resembling a mummy” in her car.