More than 20 members of an isolated Amazonian tribe have made contact with the Brazilian authorities amid growing fears that they are being driven from their forest home by drug smugglers or illegal loggers.

The implicit plea for sanctuary, support and weapons follows encounters in June and July that were captured on video.

This time 23 men, women and children, probably from the same tribe – crossed the border from their territory in Peru to seek help from Brazilian government officials, despite a long reluctance to make contact with the outside world.

Brazil's health ministry is monitoring the physical condition of the group at the Xinane monitoring post near the Envira river in Acre state. They appear healthy but, lacking antibodies against common diseases, they are taking a considerable health risk through contacts after which many tribes have been decimated by flu epidemics.

They are aware of such dangers, but appear to be more frightened of attacks on their territory by intruders. They are said to have confirmed reports that elder tribesmen were massacred and their homes burned by outsiders.

Their migration has disturbed settled communities of the Asháninka indigenous group, as the tribe have stolen food, clothes and weapons from many homes.

The Brazilian government now faces a tough decision on the best way to help them and avoid the tragedies that have followed so many previous contacts.

The National Indian Foundation (Funai) recently reopened the base at Xinane, which it had abandoned in 2011 after attacks by drug traffickers, who run a lucrative cocaine trail across the border from Peru – the world's biggest coca producer. But long-term observers of the situation say protection on the Peru side of the border is negligible and resources for support on the Brazilian side are inadequate.

José Carlos Meirelles, a frontiersman who has spent more than 20 years as an official in the region, said Brazil had a responsibility to help the young tribesmen who had made contact, otherwise there was a danger that another tribe would be wiped out. "They are asking Funai to do what the Brazilian state has the duty to do. They should not need to ask, it is our obligation," he told Blog da Amazônia.

Survival International, the movement for tribal people's rights, urged the Peruvian government to do more to protect its isolated indigenous communities. "The accounts given by these Indians – of the killing of their relatives, and the burning of their houses – were incredibly disturbing," said Stephen Corry, the group's director.

"This appears to have taken place on the Peru side of the border, probably at the hands of the illegal loggers and drug traffickers whose presence has been known of for years. What will it take for the Peruvian government to actually protect these tribes' territory properly?"

Survival has launched a letter-writing campaign to urge the governments of the two countries to provide more support for the tribes.