The sackings of Agriculture Department chief Andrew Metcalfe, Industry Department secretary and former Labor Party adviser Don Russell, and Blair Comley at Resources, Energy and Tourism were announced soon after Prime Minister Tony Abbott and his ministry were sworn in by the Governor-General on Wednesday.

Mr Abbott also said he had recommended international aid organisation AusAID be integrated into the Department of Foreign Affairs and Trade to more closely align aid and international relations.

Fraser MP Andrew Leigh slammed the decisions. ''Sacking departmental heads sends a clear message that the government doesn't value frank and fearless advice, but wants a flaccid and fearful public service,'' he said.

''Mr Abbott promised that all public service job losses would be by natural attrition.

''Today, he broke that promise.''

Community and Public Sector Union national secretary Nadine Flood called the decisions a ''very negative message to public sector employees''.

''These high level sackings have sent shockwaves across the service and have done nothing to calm concerns over job security,'' Ms Flood said. ''With right-wing think tanks and business leaders urging Tony Abbott to cut harder and deeper, public sector workers are looking for a steady and calm signal from the new government.''

Ms Flood said the new government's promised 12,000 public service job cuts and changes to AusAID administration were concerning.

''And from what I'm hearing, already senior people in the public service are tearing their hair out about how Prime Minister Abbott's cuts are going to work.''

Foreign Affairs Minister Julie Bishop said AusAID director-general Peter Baxter had taken extended leave on Wednesday.

Greens overseas aid spokeswoman Senator Lee Rhiannon described the changes as ''arrogant''.

''The new Prime Minister has sent a clear signal - Australia is selfish, and even though we are one of the wealthiest countries in the world, we are not going to bear our ethical and humanitarian responsibility to alleviate global poverty,'' she said.

''Keeping DFAT and AusAID separate ensured our commitment to poverty alleviation was not compromised to further Australia's national interest.

''This barrier no longer exists.''

She said a hostile and aggressive foreign policy was evident in the early days of the Abbott government, a position she said was favoured by neoliberals.

A recent Newspoll conducted for AusAID found 85 per cent of Australians supported funding for overseas aid programs.