All diplomats attending the United Nations General Assembly in New York next week will have to provide proof of vaccination, the city government confirmed Wednesday.

Delegates must be vaccinated to enter the debate hall, the mayor's office told the assembly president in a letter dated September 9.

They must also be vaccinated if they want to eat or exercise indoors, the letter added.

New York began enforcing a vaccine mandate on Monday, requiring proof of at least one shot for many indoor activities, including restaurants and entertainment venues.

The letter signed by New York City's health commissioner and confirmed by his spokesman said the UN debate hall was classified as a "convention center," meaning all attendees must be vaccinated.

"They must also show proof of vaccination prior to dining, drinking or exercising indoors on the UN campus, and in order to partake in all of New York City's wonderful entertainment, dining and fitness activities," he said.

The letter also reminded diplomats that New York state requires everyone to wear masks on public transport.

"New York City strongly encourages universal mask use indoors regardless of vaccination status," the note added.

The 76th session of the General Assembly starts on Tuesday and finishes the following Monday.

It will be a combined in-person and hybrid event after last year's event took place virtually because of the pandemic.