A Chinese man has been reunited with his son after a 24-year search that saw him travel over 500,000km (310,000 mi) on a motorbike across the country.

Guo Gangtang's son had been snatched aged two by human traffickers in front of their home in the province of Shandong.

His son's disappearance actually inspired a movie in 2015, which starred Hong Kong superstar Andy Lau.

Child abductions are a big problem in China, with thousands taken every year.

According to China's Ministry of Public Security, the police were able to trace the son's identity using DNA testing. Two suspects were later tracked down and arrested, said a Global Times report.

The suspects, who were dating at the time, had planned to kidnap a child with the intention of selling him for money, said a report by China News.

After spotting Mr Guo's son playing alone outside his home, the female suspect identified only by her surname Tang grabbed him and took him to the bus station, where her partner, named as Hu, was waiting.

The couple then took an intercity coach to neighbouring Henan province and sold the child there.

Local media reports say Guo's son was found still living in the province.

Guo and his wife cried and hugged their son when they were reunited in Liaocheng, Shandong, on Sunday, state media CCTV reported.

"My baby, you came back!" said the mother, whose name was not released, in a video of the reunion.

"Now that the child has been found, everything can only be happy from now on," Guo told reporters.

Lau, who got to know Guo while preparing to play him in the film Lost and Love, congratulated him.

"I'd like to say to Brother Guo that I admire your persistence," he said, according to the South China Morning Post.

After his son was abducted in 1997, Guo reportedly travelled to more than 20 provinces around the country on the back of a motorbike chasing tip-offs.

In the process, he broke bones in traffic accidents and even encountered highway robbers. Ten motorbikes were also damaged.

Carrying around banners with his son's picture on them, he is said to have spent his life savings on his mission, sleeping under bridges and begging for money when he ran out of cash.

He also became a prominent member of missing-persons organisations in China, and helped at least seven other parents reunite with their abducted children.

In China, the abduction and trafficking of babies has been a problem for decades.

In 2015, it was estimated that 20,000 children were being abducted each year in China. Many of them are sold into adoption, both domestically and overseas.

Both heart-breaking and heart-warming

Child trafficking has been an enormous social problem in China with tens of thousands of unsolved cases remaining.

It appears to be so widespread that a few years ago, when the police introduced a phone app to report crime, "child abduction" had its own front-page category along with the likes of theft, drug dealing and murder.

It has clearly caused massive pain in the community, not the least of which because - in some cases - there appear to have been "insiders" like relatives or village neighbours who have assisted in the abductions.

In one particularly distressing example, children were kidnapped and made to work in a brick factory in a neighbouring province.

This year's big DNA drive by the police seems to be working in terms of finding some of those taken quite a while ago. But it would be hard to solve more recent cases in this way because the strategy relies on people coming forward for blood tests and children (who may not even know they had been abducted and sold to their current parents) are hardly going to be presenting themselves for blood tests.

Either way, given the bleak nature of the situation and the desperate sadness of many who've lost their children, seeing Guo Gangtang reunited with his son after decades of perseverance has been both heart-breaking and heart-warming at the same time.

BBC