Public servants about to be dumped from the abolished Australian Valuation Office have been gagged from venting their feelings to reporters or on social media as the political row over the office's closure rages on.

Australian Taxation Office bosses have confirmed 200 valuation office job cuts will be included in a planned Tax Office cull of 900 full-time positions this year.

The man who announced the closure on Friday, Parliamentary Secretary to the Treasurer Steven Ciobo, says Labor is responsible for the AVO's demise, denying claims from his opposition counterpart Andrew Leigh that the closure was ideologically motivated.

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A public sector valuation insider has warned that the loss of the AVO will leave the welfare system more vulnerable to rip-offs.

The office's staff throughout Australia were warned not to talk to news organisations and to watch their step on social media platforms such as Twitter and Facebook.

''Any statements, answers to media questions or comments must not be provided, unless you are the pre-approved spokesperson,'' workers were told in an all-staff bulletin.

''You should also be careful with any use of social media during this time as you must not provide comment which might be interpreted as an official statement on behalf of the ATO/AVO.''

The statement insists the agency was not scrapped simply to deliver job cuts, saying: ''The AVO numbers are included as part of the 900 [ATO job cuts].

''However it is not true to say that the closure of the AVO is about the need to reduce ATO staff.

''It is about the sustainability of the AVO as a fee-for-service agency.''

Mr Ciobo hit back at criticism from Dr Leigh that the closure was ideologically motivated.

Mr Ciobo wrote on Monday that Labor's efficiency dividends were the main reason the AVO's work dried up. ''My decision to close the Australian Valuation Office was a practical one, not an ideological one,'' Mr Ciobo wrote.

''Labor's Andrew Leigh ignores the fact that it was his party, when in government, that required departments to reduce their spending on AVO services, with the Department of Human Services alone reducing spending by more than 50 per cent.''

A public sector valuation expert, speaking on condition of anonymity, said the closure would be costly to the nation's welfare system in the long term.

''The AVO would save the governments millions of dollars in welfare payments,'' the insider said. ''This is classic case of short-term gain at the expense of far greater long-term losses.''