Australia has the world’s fastest mobile internet but patchy coverage means we only have access to it 58 per cent of the time.

With an average download speed on 4G networks of 24.5 megabytes-per-second (mbps), Australia is more than two Mbps ahead of second-placed Italy.

But the country is ninth when it comes to coverage, according to a new report by British firm OpenSignal, which tracks global download speeds using data from its phone apps which are used by about six million 4G customers worldwide.

Australians have access to 4G networks 58 per cent of the time. First-placed South Korea, by contrast, has access 91 per cent of the time.

Australia’s impressive average speed was driven largely by Telstra, which averaged 23.8 mbps with 64 per cent availability.

Optus averaged 19 mbps at 48 per cent coverage, while Vodafone was not included in the report.

A Vodafone spokesman said the telco’s omission was curious given it launched 4G networks in Australia’s major cities in June 2013.

The spokesman pointed to OpenSignal tests which in January found Vodafone offered the fastest 4G download speeds of any telco in Sydney and Melbourne.

OpenSignal did not respond to questions.

Australia carriers have upgraded from slower 3G networks over the last three years to service a growing demand for mobile data. According to OpenSignal, 4G technology offers speeds more than five times faster than 3G.

Telstra introduced Australia’s first 4G network in September 2011, followed by Optus in 2012.

The new data, compiled in the second half of 2013, showed Australia’s overall average speed has risen by 42 per cent since the same period in 2012.

OpenSignal said speeds tend to drop as a carrier takes on more users.

“This is the reason that some countries have improved since our last report a year ago, while others have worsened.”

Average speeds in the US dropped to 6.5 mbps, down from 9.6 in the previous report, published in February 2013.