China may have the most internet users in the world, but its average broadband internet speed is just 2.4Mbps -- putting it in 141st place among 200 countries tested, according to a new report.

By contrast, the United States is the 20th-fastest country, with an average broadband speed of nearly 26Mbps.

The report -- based on data from M-Lab, a partnership between Google Open Source Research, Princeton University's PlanetLab and others -- ran 163 million individual speed tests in 200 countries.

It found that overall, broadband internet speeds have risen 23 percent over the past year -- although that improvement is focused on countries that already have relatively fast speeds.

The report found that faster countries are improving more quickly. (Picture: Cable)

There are several reasons why China is behind.

In general, the larger the nation is, the slower the internet access tends to be. Covering a massive area with high-speed connections simply takes more time, effort, and money.

On the other hand, a small and well-developed region like Hong Kong, for example, enjoys an average broadband speed of over 26Mbps.

The relatively low average speed in China also masks a big difference between major cities and less developed areas. For instance, average speeds in Shanghai and Beijing are well above the national average -- while less prosperous regions like Xinjiang and Qinghai in western China tend to lag behind.

Last year, a report from China’s Broadband Development Alliance put Shanghai’s broadband speed at 18.41Mbps.

And while the new report focuses only on broadband speed, for many Chinese internet users it might not matter much. That's because in China more people are going online using their smartphones instead of laptops or PCs.

Even as it trails behind major countries in broadband, China remains ambitious. It’s currently battling with the US to get the upper hand on developing a 5G network.