Labor has stepped up its attacks on negative gearing, releasing statistics showing soaring investment property sales in Sydney which they claim underline the city's housing affordability discord.

Key points: The average house price in Sydney is more than $1.1 million

The average house price in Sydney is more than $1.1 million Government figures show the city's investor market is surging

Government figures show the city's investor market is surging The number of NSW properties bought to rent out has grown by 61 per cent since 2013

At a joint press conference in central Sydney, Federal shadow treasurer Chris Bowen and NSW Labor leader Luke Foley attacked the investment-property tax break and said Australia's biggest city, where the average house price is more than $1.1 million, had an "affordability crisis".

But hours earlier, across town at Homebush in the city's west, the Federal Minister for Urban Infrastructure Paul Fletcher was less keen to talk about housing.

"I suspect the people of Sydney have a lot more things that they're thinking about on a daily basis than that," Mr Fletcher said.

The data released by Labor showed the number of rental properties in New South Wales snapped up by investors had grown by 61 per cent since 2013.

Of those, more than half were in Sydney. Labor obtained the numbers using freedom of information laws.

Gladys Berejiklian used her first press conference as NSW Premier on Monday to highlight housing affordability as one of her top three priorities.

Mr Bowen said Australians were worried about house prices.

"Australia has the most generous tax concessions for property investment in the world," he said.

"We also have, despite the Premier's claims to the contrary, a housing affordability crisis."

The figures from the Office of State Review show the number of properties in Sydney bought specifically to rent rose from 1,660 per month in 2013 to 2,670 last year.

Number of first home buyers in freefall

Since 2011, the percentage of first home buyers entering the market in NSW has fallen from 18 per cent, to 8 per cent.

On Tuesday, Sydney's affordability crisis was laid bare by an international survey which ranked the Harbour City's house prices behind only Hong Kong.

Labor heavyweights Chris Bowen and Luke Foley have attacked negative gearing. ( ABC News and AAP: Paul Miller )

Negative gearing is a key policy difference in Canberra, with the Turnbull Government ruling out changes to the investment-property tax break.

However, NSW Labor leader Luke Foley said the policy needed reform.

"Currently the balance is tilted unfairly against the interests of those seeking to purchase a first home," he said.

"Nowhere is it a greater problem than here in Sydney, Australia's largest city."

Increasing supply a top priority for Berejiklian

Premier Berejiklian has made it clear she believed an increase in supply could be the most effective way to combat rising house prices.

She revealed she had already spoken to Prime Minister Malcolm Turnbull about housing affordability.

"I can appreciate why my colleagues at a Federal level aren't getting into the specifics of a debate," she said.

"What what has been shown previously is that if you make decisions without consideration in relation to housing, you can unintentionally create more heat in the market, which puts upward pressure on prices."