A Holyrood committee has raised concerns over powers being given to ministers in the Scottish Government's controversial Brexit Bill.
The Delegated Powers and Law Reform Committee is scrutinising the UK Withdrawal from the European Union (Legal Continuity) (Scotland) Bill which is being rushed through Holyrood.
It has been introduced as emergency legislation due to an ongoing dispute with UK ministers over devolved powers returning from Brussels.
Brexit Minister Michael Russell said the bill will act as a "back-stop" in case agreement cannot be reached over the UK Government's European Union (Withdrawal) Bill.
He told the committee that while the Scottish legislation heavily mirrors the UK bill - which will transpose EU law into domestic law in time for Brexit - Scottish ministers have "made positive changes" to address "defects" identified in that legislation.
Concerns have been raised over so-called Henry VIII powers, which give UK ministers far-reaching authority to amend laws to make them suitable for the UK statute book.
The committee questioned Mr Russell over similar provisions for Scottish ministers contained in the emergency bill.
Conservative MSP Alison Harris asked for "reassurances that powers can only be used to make changes to make the law work efficiently on exit".
Mr Russell said a "test of necessity" had been added to the Scottish bill, alongside additional limits on the powers, and an enhanced role for the Scottish Parliament.
"That test is pretty severe for the minister to meet," he said.
He added: "We have to be able to say how would we have a working and functioning system after the day (of Brexit) itself, and if it's not going to be a working functioning system, if it is going to fail because the legislation is not there, then that's a situation in which we have to move, now sometimes to move rapidly, but with greater scrutiny than was previously the case under the UK bill."
The minister also faced questions over provisions which give the Scottish Government the ability to ensure that devolved law in Scotland keeps pace with post-withdrawal developments in the EU.
The measure is time-limited to five years with the possibility to extend it for longer.
Labour MSP Neil Findlay said: "Someone could be reading that section, and say 'they want powers to implement EU law that they like for five years, but that could continue for as long as they want'.
"You can understand why some people could look at this and say this is just looking to frustrate the whole process."
Mr Russell said the measure would be scrutinised by the Scottish Parliament.
"It doesn't keep us in the EU...it's being taken for practical reasons which are helpful to a variety of sectors," he said.
"It will be up to ministers to bring forward their proposals. It'll be up to Parliament to accept or otherwise those proposals."
"It allows the continuation of the present situation in key areas, which is what many people wish to see, and we think this is a useful thing to do."