On LDOCE, at the definition page of "neither", there is one definition that describes the word as a conjunction, with the sentence:
The authorities were not sympathetic to the students’ demands, neither would they tolerate any disruption.
Is the usage of the word after a comma as a conjunction by itself as in the sentence really grammatical? If so, how often is "neither" used like this? Is this usage of "neither" as common in American English as it is in British English?
Thank you in advance!