Around sixty men and women in traditional garb and headdresses, some carrying babies, formed a human barricade at the main entrance as tens of thousands of delegates were arriving.

Beneath a blazing sun, the group demanded a meeting with Brazilian President Luiz Inacio Lula da Silva and stood their ground as diplomats were ushered through side doors into the venue.

It was the second time this week that Indigenous protesters have disrupted the climate talks in Belem, a city on the Amazon River and the gateway to the world's largest rainforest.

The demonstrators had "strong and very legitimate concerns," said COP30 president Andre Correa do Lago, who skipped a morning event to go outside to meet the group.

Correa do Lago was handed a document outlining their concerns before holding consultations with the group in a nearby hall where Indigenous people of all ages sang, danced and chanted.

"We had a very positive, very constructive dialogue," Correa do Lago said following the session.

"We will seek to address all the concerns they have."

Dozens of armed soldiers and military police were guarding the venue entrance, but the United Nations said in a message to attendees that there was "no danger."

- 'Never heard' -

From the Munduruku community, the Indigenous protesters are seeking to progress the demarcation of their traditional homelands.

They also contest the Ferrograo project, a nearly 1,000 kilometer (620 mile) railway intended to cross Brazil from west to east to transport grain production.

"Fighting for our territories is fighting for our lives," read a banner held by one Munduruku demonstrator.

"Come on, Lula, show yourself!" shouted Alessandra Korap, an Indigenous leader.

"We want to be heard, we also want to participate in the negotiations," she added. "We have too many problems."

Lula is a self-proclaimed ally of the Indigenous cause.

He has advanced recognition of tribal groups, cut deforestation in the Amazon and appointed a widely respected figure to head the first-ever Ministry of Indigenous Peoples.

But many deplore the slow pace of demarcating Indigenous lands and the oil exploration launched in October near the mouth of the Amazon.

On Wednesday, the iconic Indigenous chief Raoni said he would "make an appointment" with Lula over the oil project and Ferrograo and "if necessary, I'll give him a good talking-to."

After about two hours, the thousands of attendees waiting outside in the sun were able to get into the venue through the main gate.

Brazil on Thursday defended security at COP30 after concerns were raised earlier this week over the previous demonstration.

On Tuesday evening, Indigenous protesters and their supporters stormed the negotiation venue and clashed with guards in scenes rarely witnessed at a UN climate conference.

When asked by AFP on Thursday about the possible need for additional security measures in Belem, Correa do Lago replied: "No need, it was really a minor incident."