More than 500 bicycles from China's flourishing bike-sharing companies have been dumped in huge piles on the streets of the southern city of Shenzhen, reports said.

Pictures showed jumbled stacks of vehicles nearly three metres high, with handlebars, baskets and other parts scattered on the ground.

City streets around the country have seen an explosion of the colourful bikes that users can rent on demand with a smartphone app and then park wherever they choose.

The sharing economy is taking off in China, where ride-sharing and AirBnb are increasingly commonplace.

New tech firms such as Ofo and Mobike, with their rival fleets of bumblebee yellow and fluorescent orange bikes, have been locked in a cutthroat battle for users and profit.

But problems have arisen when clients have abandoned their cycles.

"Some people these days just have really bad character," a man named He, who lives near where the stacks appeared, told the Southern Metropolis Daily.

"When they're done using [the bike] they just throw it away somewhere, because they've already paid."

In the past few days he witnessed people demolishing the bikes before discarding them on the side of the road, he said.

Residents told the paper that bikes have been piling up over the past week, either parked haphazardly by careless users or stacked by local security guards trying to clear narrow residential alleys and footpaths.

Zhuang Chuangyu, a representative to Shenzhen's municipal people's congress, said that the city needed to step up regulation of the ballooning bike-sharing industry in order to improve traffic conditions and safety standards, especially since primary and secondary school students often used the bikes.