image sourceGetty Imagesimage captionThe elephants have tucked into villagers' crops on their long migration route

More than 150,000 people have been evacuated from the path of a herd of migrating elephants, Chinese officials have said.

Authorities in south-western Yunnan province feared conflict between residents and the 14 Asian elephants which have been on the move for months.

More than 25,000 police officers using vehicles and drones have monitored the herd, state media report.

The protected animals left a nature reserve in Yunnan about 17 months ago.

Since then they have made international headlines with an extraordinary 500km (300-mile) trek that has seen them wander through fields, towns and cities, eating millions of dollars worth of crops and damaging buildings.

As the herd approached settlements, local residents were temporarily relocated.

By June the animals had reached the outskirts of the provincial capital of Kunming.

Efforts to head them off and send them back to the Mengyangzi Nature Reserve initially failed but eventually the herd turned around and began to head home.

image sourceChina Central Television (CCTV)image captionDrones were used to keep an eye on the herd, seen here asleep in a forest

Wan Yong, who heads the team monitoring the elephants, told a news conference on Monday that the herd had crossed the Yuanjiang River and was continuing to head south. Electric fences, bait and artificial roads have been used to ensure the animals followed the correct path.

Experts say it is unclear exactly why the elephants left their usual habitat to embark on the journey. Some have suggested an inexperienced leader may have led the herd astray, while others believe the elephants could have been searching for a new habitat.

The Asian elephant is an endangered species. China has only about 300 wild elephants, mainly living – like the wandering herd – in the south of Yunnan province.

media captionThe elephants have been filmed in a number of Chinese cities