Melbourne has cemented itself as Australia's fastest-growing city.

The Victorian capital, along with Sydney and Brisbane, accounted for more than 70 per cent of the country's population growth in the 2016-17 financial year.

But scratch beneath the surface and the story of what drives growth varies significantly in Australia's three largest cities.

For the first time the Australian Bureau of Statistics (ABS) has crunched the numbers and broken down the growth into three categories:

Overseas migration

Overseas migration Internal migration, flows in and out of a region from and to other parts of Australia

Internal migration, flows in and out of a region from and to other parts of Australia Natural increase, in other words more births than deaths

Sydney

Sydney is losing people to other parts of Australia. ( ABC News: Graeme Powell )

Australia's largest city now has a population of 5.1 million, with a growth rate of 2 per cent.

Sydney's biggest driver in the 2016-17 period, overseas migration, accounted for about 85,000 of the increase of 102,000.

That was significantly higher than Melbourne's 64 per cent.

Sydney's second most powerful driver, natural increase, saw the population swell by 35 000, compared to 36 000 in Melbourne.

But when it comes to internal migration, Sydney is on the backfoot.

Melbourne boasted a net increase of 9,200 people, while Sydney recorded a net loss of 18,100.

Professor of Demography at Macquarie University, Nick Parr, said Sydney was losing people to other parts of Australia.

"The two regions which are gaining people from Sydney are the remainder of New South Wales and also Melbourne," Professor Parr said.

Melbourne

There are now 4.9 million people living in Melbourne. ( ABC Open contributor Shayne T Wright )

Melbourne has recorded its highest-ever net annual population increase of 125,000.

There are now 4.9 million Melburnians, with the growth rate currently sitting at 2.7 per cent.

The city also boasts the fastest-growing suburb in the country, Cranbourne East, which saw its ranks swell by 27 per cent from 27,000 residents in 2016 to 34,000 in 2017.

Melbourne's population is now just 200,000 below that of Sydney's, which itself saw a record an annual increase of more than 100,000 people.

Overseas migration was Melbourne's biggest population driver in the 2016-17 period, accounting for 64 per cent of growth, followed by natural increase at 29 per cent.

Internal migration boosted Melbourne by 9,200 people.

Brisbane

Brisbane has recorded its fastest population growth in four years. ( Supplied: Brisbane Festival )

Brisbane recorded a 2 per cent growth rate in the 2016-17 period, the city's fastest growth since 2012-13.

It increased the Queensland capital's population by 48,000 to 2.4 million.

At the same time the area with the largest decline in population nationwide was recorded in Queensland, with Collinsville in the Bowen Basin, registering a drop of 5.1 per cent.

Brisbane's main source of growth was also overseas migration, accounting for 38 per cent of the population change.

But unlike Sydney and Melbourne, the numbers are more evenly spread across the three measured components.

Natural increase accounted for 37 per cent of growth, while internal migration accounted for a quarter increase.

The fastest and largest-growing area in Queensland in 2016-17 was Pimpama on the Gold Coast, which grew by 3,000 people, or 31 per cent, largely due to internal migration.

Pimpama on the Gold Coast is the fastest and largest-growing area in Queensland. ( ABC News )

Other capitals

The fourth-fastest-growing city was Canberra with an increase of 1.7 per cent to 410,000.

Growth in Western Australia's Perth, population of just over 2 million, was low at just 1 per cent, slightly behind Tasmania's capital Hobart, which has 227,000 people, at 1.1 per cent.

At 0.7 per cent, Adelaide recorded its lowest growth rate since 2003-04.

The South Australian capital now has a population of 1.3 million.

Growth was slowest in Darwin at 0.5 per cent, taking the population there to 147,000.

Demographers said the new figures, combined with the breakdown of population drivers, were invaluable for infrastructure planning.

'We need to look beyond just national statistics', Professor Parr said.

'There are very different patterns of population growth in different parts of Australia and the issues that accompany these different population patterns can differ substantially."