Brazil's President Luiz Inacio Lula da Silva championed the holding of the global conference in the world's largest rainforest but he has come under pressure about the hotel chaos in the poor northern city.

Organizers reported in a statement that only 79 of 198 countries have secured lodging, while 70 others were still in negotiations for places to sleep during the November meeting.

Some 50,000 people are expected in Belem, home to 1.4 million residents -- more than half of whom live in shantytowns.

With a shortage of traditional hotel rooms, conference organizers have scrambled to find alternative accommodation in private homes, universities and schools, and even two cruise ships docked in the harbor some 20 kilometers (12 miles) from the conference center.

Lula has batted away concerns and requests to move some events to other cities, saying in February that delegates can "sleep under the stars."

COP30 could be "the most exclusionary in history" due to its prices, the Brazilian NGO Climate Observatory warned in August.

To ease the pressure, the United Nations is boosting its daily subsidy for delegates from 144 countries from $144 to $197, a UN spokesperson confirmed Wednesday.

The Brazilian government welcomed the move but said it would "not cover costs entirely."

The UN requires accommodation costs of $100 a night for low-income nations -- a number hard to come by in Belem on Airbnb, Booking.com, and the official accomodation platform.

To ease demand for hotel rooms, Brazil moved the meeting of heads of state to November 6 and 7, several days before the start of the wider conference -- but this has not been enough to significantly bring down prices.