(Adds quotes from new leader, privatisation policy)

By Colin Packham

SYDNEY, Jan 23 (Reuters) - Australia's most populous state and biggest state economy, New South Wales, appointed a new leader on Monday who is expected to continue infrastructure investment through privatisation.

Gladys Berejiklian, a former state treasurer, was elected unopposed in an internal Liberal Party vote after the surprise resignation of state leader Mike Baird last week.

The New South Wales (NSW) economy accounts for 31 percent of Australia's gross domestic product and is larger than the economies of Thailand, Malaysia and the Philippines.

Its economy, worth A$530 billion ($398.19 billion), has seen sustained investment in infrastructure funded by a wave of privatisations in recent years.

The most recent was the A$16.2 billion ($12.25 billion) sale of power networks Ausgrid in October and TransGrid to an international consortium of funds for A$10.26 billion in November 2015.

The next slated sale is a 50.4 percent stake in Endeavour Energy, which powers parts of southern Sydney and is expected to attract bids of around A$4 billion.

Berejiklian said she will continue infrastructure investment, while maintaining control of the state's budget, likely increasing the number of assets that may be privatised.

"A strong economy means more jobs. It means better services and it means putting money where it is needed the most," Berejiklian told reporters in Sydney.

Berejiklian also highlighted housing affordability as a priority for her government, a politically sensitive issue particularly in the state capital Sydney which is experiencing a housing boom pricing many first-time buyers out of the market.

Median home prices in Sydney, Australia's biggest city, have surged 10.6 percent to A$800,000 in the past year, research from CoreLogic RP shows.

($1 = 1.3226 Australian dollars) (Reporting by Colin Packham. Editing by Jane Wardell, Lisa Von Ahn and Michael Perry)