Image copyright Getty Images Image caption The private university in upstate New York has more than 22,000 students on campus

An investigation is under way after US officials received reports a "white supremacist manifesto" was sent to students at Syracuse University.

It was the latest in a spate of racist incidents that have been reported on the upstate New York campus.

The school said it has added security as the reports are investigated.

But critics - including some students and New York Governor Andrew Cuomo - say the university's response has not been sufficient.

The manifesto was posted online late Monday night before allegedly being sent to the phones of several students inside a campus library via Apple AirDrop, a file-sharing service.

Police say the manifesto appears to be the same one written by the man suspected in the massacre at two New Zealand mosques in March. It did not contain a specific threat to Syracuse University.

Mr Cuomo, in a statement on Tuesday, criticised university Chancellor Kent Syverud's response, demanding a probe into the surge of racist incidents.

The Democrat governor said: "They have not been handled in a manner that reflects this state's aggressive opposition to such odious, reckless, reprehensible behaviour. That these actions should happen on the campus of a leading New York university makes this situation even worse."

Mr Syverud promised action and acknowledged "concrete concerns related to the environment for diversity and inclusion on our campus".

A criminal investigation has been opened, with the FBI assisting local and state law enforcement.

What else has happened?

Since early November there have been several reports of racist incidents targeting various groups, including black, Asian and Jewish students.

On Saturday night, racial slurs were allegedly hurled at a black female student by members of a fraternity. In response, the school suspended the fraternity involved as well as social activities for all fraternities.

Days before that, a swastika was drawn in the snow on the lawn of an apartment complex where students live.

There have also been multiple accounts of racist graffiti towards black and Asian students in campus buildings.

Students have also been protesting against the university's response to the events with sit-ins at campus buildings. Student demands include expelling those responsible for the reported incidents and mandatory diversity training for new staff.

An anonymous donor has offered a $50,000 (£38,700) reward to help find those involved in the incidents.

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