Drought-afflicted herders have been ordered to remove their cattle from Tanzania’s national parks, where they had moved in a bid to find new food sources, the Tanzanian government said late on Monday.

Thousands of heads of cattle, goats and sheep have crossed into Tanzania from neighbouring Kenya and Uganda in recent months searching for water and fresh pasture, according to government officials.

This has placed increasing strains on the east African nation’s wildlife and has affected the tourism industry, they said.

All herders– both foreign and Tanzanian– have until June 15 to remove their animals from the protected areas, Tanzanian vice president, Samia Hassan Suluhu, said on Monday.

Failure to vacate the national parks will result in forceful eviction, she said.

"We would not want to see any livestock from either within or outside the country encroach and tamper with our national park ecosystems,” Suluhu said.

Worsening drought in many parts of East Africa had forced herders to move cattle into areas protected for wildlife in a desperate bid to find new food sources, she said.

Government officials said the situation has also sparked deadly conflict in some parts of the country as local farmers and pastoralists clash over dwindling pasture and water supplies.

Suluhu said it was estimated that as many as five million livestock from Uganda and Kenya were grazing and destroying the environment in the northern Kagera, Arusha and Geita regions.

"Livestock owners from outside Tanzania don’t want to destroy their (own) environment. So they bring their animals to feed in Tanzania,” she said.

This is not the first time Tanzania has sought to remove cattle from protected wildlife areas.Last year, government authorities were widely criticised for attempting to evict unauthorised squatters and their

animals from the game reserves, said the Dar es Salaam-based Legal and Human Rights Centre.

In a telephone interview with the Thomson Reuters Foundation, Daudi Kivanda, a herder in Tanzania’s northern Geita region said that while he will heed the government’s call, moving will not offer a lasting solution for farmers.

"The government promised to apportion special grazing areas (but) it hasn’t fulfilled that promise. Where can we take our cattle to graze?” he said.

Tanzania has approximately 21 million heads of cattle, the largest number in Africa after Ethiopia and Sudan, according to Ministry of Agriculture Livestock Development and Fisheries data. It estimates that livestock contributes to at least 30 per cent of agricultural GDP.

However, wildlife conservationists are increasingly concerned about the impact of farming and livestock on national parks and game controlled areas.

Stephano Qulli, chief park warden at the northern Tarangire National Park, said the destruction of wildlife corridors due to overgrazing has threatened the population of wild animals, including wildebeest, which have suffered a population drop from more than two million to 1.5 million over the last decade.

"When human beings trespass in national parks, they destroy animal corridors which help wild animals in calving,” he said.