New York prosecutors have dropped all criminal against most students and activists arrested for occupying a Columbia University building to protest the Gaza war.

Of the 46 people arrested in April in connection with the occupation of Hamilton Hall, 31 had their charges dismissed on Thursday.

University officials had authorised police to enter the hall after student demonstrators inside ignored a deadline to leave.

None of the arrested students had any previous criminal history, and all were facing disciplinary proceedings, including suspensions and expulsions, by Columbia.

All 46 protesters, who were arrested on the night of April 30, were initially charged with trespass in the third degree, a misdemeanour.

Manhattan district attorney's office told a court on Thursday that they would drop the charges against 31 protesters citing "prosecutorial discretion and lack of evidence".

Prosecutors also told 14 others that their cases would be dropped if they avoided being arrested in the next six months. The defendants rejected the offer and are all due back in court on 25 July.

One other defendant, James Carlson, has two open cases against him involving separate charges, including arson for setting an Israeli flag on fire before the takeover of Hamilton Hall.

He has also been charged with damaging a police surveillance camera in while in custody. Mr Carlson has no affiliation with Columbia.

US college campuses were a flashpoint for protests against the Gaza war, which was sparked after Hamas attacked Israel on 7 October, killing about 1,200 people - mostly civilians - and taking 253 others back to Gaza as hostages.

More than 37,390 people have been killed in Gaza since then, according to the territory's Hamas-run health ministry.

Student and activists across the US have demanded that their universities, many with large endowment funds, financially divest from Israel. Divestment means to sell or otherwise drop financial ties.