Young Maasai herders are so afraid of authorities that they "flee when they see a vehicle approach", thinking it might carry representatives of foreign safari companies, the Oakland Institute report said.

Responding to the findings, Thomson Safaris said the "awful allegations of abuse are simply untrue". The company invested in Tanzania "in good faith", director Rick Thomson said in an email.

Concern for the Maasai has been raised at home and abroad by rights groups such as Minority Rights Group International and Survival International, which has warned that the alleged land grabs "could spell the end of the Maasai".

The Maasai, hundreds of thousands of cattle herders who inhabit the savannah in southern Kenya and parts of neighbouring northern Tanzania, need land to graze their animals and maintain their pastoralist lifestyle. But the land bordering Tanzania's famous Serengeti National Park is also a wildlife corridor popular with tourists.

The east African nation's government depends substantially on tourism revenue to finance its budget.

The government has prioritised safari groups at the expense of indigenous communities, said Hellen Kijo-Bisimba, head of the Tanzania Legal and Human Rights Centre.

"The government has been reviewing boundaries and subsequently evicting communities in the name of conservation," she told The Associated Press. "In my understanding the conservation should have been made to benefit people, and if people are affected then it calls for worries. The Maasai community (is) indeed suffering."

A court in the regional capital, Arusha, ruled against Loliondo's Maasai in 2015 when it decided that Thomson Safaris legally purchased 10,000 acres of a disputed 12,617 acres in 2006. The Maasai appealed and the case is pending.

Thomson, of Thomson Safaris, said in Thursday's email that "witnessing" the wildlife in Tanzania was a passion.

"But what made Tanzania so alluring was not just the wildlife, but the people," he said. "When people return from a safari with us, they say how magnificent the wildlife was, but that what was so extraordinary were the people they met."

Tanzania's Tourism Permanent Secretary Gaudence Milanzi denied the Maasai are being targeted, saying the government is working to improve their welfare by embracing modern methods of livestock keeping.

"There is no single group of people, say Maasai, who are intimidated, arrested, beaten or forced out of their land," Milanzi said.

AP SN/CJB