Biting at nursery

My son goes to nursery 3 mornings a week, he has been in this nursery since April. His old one closed down due to the land being sold and we had no issues. THis one we have had a few, this time it is my son biting. I am not denying that he is, if they say he is he is. First time was provoked another kid took a toy off him and he bit, he can't talk and we are getting help for this. Yesterday he bit two kids unprovoked supposedly. Today he bit one. I have asked advice on how to handle this, he is not.like this at all at home. It is me and dad at home, he is an only child he does have cousins but sees them rarely and I do have a couple friends who also have kids. I do work full time, me and my husband juggle between us childcare. I am asking for advice on how to approach this with my son. He doesnt really listen to gentle parenting, the only way I have managed to make him stop naughty behaviour was naughty corner, I have given the nursery permission for a bit more sterner approach. But yeah at a bit of a loss.