The Greens and the ACT Council of Social Service say the figure highlights the urgent need for more affordable and public housing in the nation's capital, while the Canberra Liberals fear the situation will worsen without policy changes.

Housing ACT received 1899 applications for social housing assistance in 2018-19, up from 1178 in the previous financial year, according to new annual report figures.

Just four per cent of those who applied last year were placed in housing, with waiting times now out to beyond 1120 days for standard applicants.

There are more than 2370 people on the government's public housing waiting list, a near 30 per cent rise from 18 months ago.

In its 2018-19 annual report, the Community Services directorate, which oversees Housing ACT, said low-income households were being "crowded" out of the city's private property market, driving an increase in demand for social housing and homelessness services.

A government spokeswoman said there had been a "tightening" in Canberra's rental market in the past year, leaving "few" affordable housing options for low-income households.

Just 1.3 per cent of rental properties in Canberra are vacant, according to the latest Domain figures.

Canberra's rental market has become increasingly expensive and competitive on the back of strong population growth, low unemployment and high household incomes.

The capital's median rent prices for houses are the highest in the nation at $550 per week, while the asking price for apartments is second only to those in Sydney.

Greens housing spokeswoman Caroline Le Couteur said Canberra's housing market was in "crisis".

"The government urgently need to deliver more affordable rental housing for people in need," Ms Le Couteur said.

"We know too many Canberrans are experiencing or at risk of homelessness, simply because there isn't housing that's affordable and available in the private market."

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ACT Council of Social Service executive director Susan Helyar said the increase in applications to Housing ACT reflected the growing number of low-income households facing housing stress.

Ms Heylar said moves to simplify and streamline the application process might have also contributed to the increase.

She said there was an "urgent" need to build more public housing units, as well ensure the government's 15 per cent target for affordable housing in new land releases was adhered to.

"We believe affordable rental housing is the biggest gap in the Canberra market," she said.

"Until this gap is breached, growing numbers of low-income will struggle to cope with keeping food on the table, their energy bills paid and their health care costs covered."

The government spokeswoman said the ACT was not immune from the "challenges of housing affordability being experienced across the country".

The Barr government last year pledged $100 million to implement its new housing strategy, which involves renewing more than 1000 public housing units across the city

An extra 200 units will also added to the territory's overall public housing stock as part of that program.

Chief Minister Andrew Barr has said the government could effectively double the size of that investment if the Commonwealth agrees to waive the territory's $115 million historic housing debt.

But opposition housing spokesman Mark Parton said pumping millions of dollars into new public housing wouldn't solve the problem.

Mr Parton said government policies were to blame for the spike in applications to Housing ACT.

He said the government had restricted the supply of land for standalone dwellings, which had driven up house prices across the board. Changes to residential tenancy laws were already forcing investors to sell up, reducing the amount of properties available for rent, he claimed.

"It is concerning," Mr Parton said of the increase in applications for social housing assistance.

"But it is of no surprise to us, and it shouldn't be of great surprise to the government. We have been saying this for a long time that this is going to happen. It is playing out at a disturbing level now."

"My feeling is that it will get worse over time. When we pick up this [annual report] a year from now, it will be diabolical."

Opposition leader Alistair Coe last week outlined plans to unlock more land for detached housing across the ACT if the Liberals win next year's election.