CANBERRA, Oct. 30 (Xinhua) -- Nearly 50 million phone calls to Australia's national welfare agency, Centrelink, went unanswered in the 12 months to June 2018.

The Department of Human Services (DHS) revealed that 48 million calls were not answered during a series of Senate hearings, saying that it was a slight improvement from the 55 million unanswered calls in 2016-17.

"We thought it was high when we were getting to 22 million, and that was 2014-15, so we've still got a significant way to go," Greens Senator Rachel Siewart told the hearing.

"It's good to see it's come down but sorry if I'm not popping any party poppers yet."

Customer satisfaction with the agency fell to 46.5 percent, 10 percent below that Centrelink hoped to achieve.

The government on Tuesday announced it would privatize 800 Centrelink call center jobs in an attempt to improve the agency's efficiency.

Centrelink is responsible for delivering a range of government payments for retirees, the unemployed, students, indigenous Australians, carers and families among others.

DHS secretary Renee Leon said her department did not consider the 2017-18 figures as "mission accomplished."

"I don't know that we're going to solve it this year, but I hope that we will continue to drive it down," she said.

The number of calls to Centrelink soared in 2016-17 in response to the agency's debt recovery controversy.

Between July and December 2016 Centrelink sent out 169,000 debt recovery letters, up from the previous average of 20,000 per year.

The spike came after Centrelink automated its data-matching with the Australian Taxation Office.

Under the revised scheme, the onus was shifted from Centrelink needing to prove the data was accurate to individuals to prove they did not owe the funds, resulting in tens of thousands of complaints.

According to the recent hearings, there were 237,000 complaints made about Centrelink in 2017-18, up 68,000 from the previous year.