The Public Service Reform Bill has been condemned by several of Scotland’s “czars”, including those responsible for young people, human rights, and freedom of information. In a highly unusual step, the Scottish Parliament’s presiding officer has also raised concerns about the bill.

The legislation is meant to “simplify and improve” the country’s many public bodies, as well as create the arts quango Creative Scotland.

However, in addition it would give ministers the power to change, merge or abolish more than 100 specified public bodies, including all health boards, children’s panels and national parks.

Also listed are several independent watchdogs, including Audit Scotland, the Mental Welfare Commission, and the Scottish Criminal Cases Review Commission.

Although many of the bodies were established by a full act of parliament, under the proposals they could be scrapped via a simple ministerial order. Some – like the Scottish Information Commissioner – were designed to be wholly independent of ministers and are funded by the Scottish parliament, yet could be axed by the government.

In written evidence to this week’s finance committee meeting, the watchdogs will demand that they be removed from the scope of the bill.

Tam Baillie, Scotland’s Commissioner for Children and Young People, said the powers were of “great concern”, and could result in “weakened rights protection for Scotland’s children”.

Kevin Dunion, the Scottish Information Commissioner, whose decisions on freedom of information (FoI) often embarrass ministers, said the powers were “inappropriate” and “anomalous”.

Despite government assurances that any changes would be merely “administrative”, he said they would “also have the effect of fundamentally changing Scotland’s FoI regime”.

Writing on behalf of the Scottish Parliamentary Corporate Body, presiding officer Alex Fergusson said he was “surprised” to see bodies funded by the parliament included in the bill, all of which are independent of government.

“We consider it is important to avoid actions which could limit or compromise that independence,” he said.

The newly established Scottish Human Rights Commission also said giving ministers sway over its operations was “not appropriate” and would undermine its independence.

The Commission for Public Appointments said the bill would give ministers “an incredibly wide and unfettered power”, which the Law Society of Scotland said was “constitutionally significant”.

A government spokesman said: “We are making public services simpler, sharper and better co-ordinated. The Public Services Reform Bill provides necessary changes to legislation to dissolve and merge more bodies and puts a new framework in place to manage future change … Any proposals would be subject to prior consultation and parliamentary approval.”

In a speech to the Liberal Democrat conference in Bournemouth today, Scottish leader Tavish Scott is due to attack the SNP for the “creeping centralisation” of government services.