The UK's electoral watchdog "strongly believes" it should test the question for any future independence referendum, MSPs have heard.

Electoral Commission bosses told Holyrood's finance and constitution committee that allowing them to test the question would give Scottish voters greater confidence in the referendum process.

The commission tested the question before the 2014 independence vote, with the body agreeing there could be "Yes" and "No" answers to the proposition: "Should Scotland be an independent country?"

However, two years later it determined in the Brexit referendum that the options on the ballot paper should be "Remain" and "Leave".

It comes on the fifth anniversary of the first independence referendum, which the No campaign won by 55% to 45% for Yes.

Constitutional relations secretary Michael Russell claimed last week there was no need for the Electoral Commission to test the question in a second independence vote.

He said it would be "very confusing" to change the question from that posed in 2014, adding that the vast majority of polling on independence since the referendum has used the same question.

But speaking to MSPs on Wednesday, Dame Sue Bruce, Electoral Commissioner for Scotland, said: "We strongly believe that the commission should be asked to test the question.

"Putting the voter at the centre of the process, we think a formal testing of the question helps to provide confidence and assurance to the voter and to the parliament posing the question in terms of the integrity of the process."

The testing process takes up to 12 weeks, consisting of focus groups and in-depth interviews with members of the public as well as expert advice before a final report is published.

Chief executive Bob Posner said the commission did not have a pre-existing view of what any future independence referendum question should be.

He told MSPs: "I think it's really important to say that we don't start with a preposition at all.

"The fact that there was in 2014 a referendum in Scotland, if we had a repeat of that referendum, it would be a very material consideration that there was a question that was in the public's minds back then and there's a familiarity, and polling since.

"So all that would be picked up as part of the assessment process but we wouldn't start with any position at all."

He added: "No one should think that just because there's been a 2016 referendum where Remain and Leave was used, there would be any reason why that would be relevant or appropriate for another referendum, or not as the case may be."

Using a Remain/Leave question, a survey by campaign group Scotland In Union to mark the indyref anniversary found 59% of Scots would vote to stay in the UK.

However, a poll last month conducted by Lord Aschroft using the 2014 Yes/No question suggested there is a 52% majority in favour of independence.

First Minister Nicola Sturgeon claims a mandate to hold a fresh independence vote before the end of this parliament, and wants to hold one in the second half of 2020.