The Scottish Tories have threatened to table a vote of no confidence in the health secretary if he refuses to hand over his parliamentary iPad.
Michael Matheson racked up £11,000 in data roaming charges on the device during a holiday to Morocco last year.
The Tories said the iPad should be handed in to check if Mr Matheson used it for constituency work, as he said.
The minister insisted the matter had already been fully investigated by parliamentary authorities.
Mr Matheson has insisted the matter was already been fully investigated by parliamentary authorities.
After initially agreeing to pay £3,000 towards the bill from his expenses budget, the health secretary confirmed last week he would pay the £10,935.74 bill personally.
A Scottish Parliament spokesperson confirmed on Monday that Mr Matheson's iPad had been examined in person by a senior IT official to ensure it was working.
They said the official reviewed the iPad's mobile data settings and data use, but stated the device did not give a "breakdown of data over a specific timeframe".
The spokesperson said the parliament had been assured the device was being used for parliamentary purposes.
A complaint about the bill was made to was also made to Police Scotland but after assessing it they decided no further action would be taken at this time.
Scottish Conservative leader Douglas Ross said "serious questions" remained unanswered.
"Despite his woolly words to journalists on Monday, it's clear the Scottish Parliament officials have not examined the browser history of his iPad," he said.
"That's the only way Mr Matheson's claims can be verified, so you'd think he'd be rushing to hand it over in order to prove that there was no personal usage.
"We need to get to the bottom of this saga once and for all, so the Scottish Conservatives are issuing the health secretary with an ultimatum: hand over the iPad, for the browsing history to be checked, and deliver a personal statement in parliament explaining the full circumstances or we'll table a motion of no confidence."
A motion of no confidence requires the support of 25 MSPs to be held. There are 31 Scottish Conservative MSPs.
Mr Matheson told BBC Scotland News that the matter had been investigated by a parliamentary IT manager, who had "access to all of the data" associated with the device.
He said he would pay all of the charges "to put the issue beyond any question whatsoever".
After the parliament confirmed its officials had not looked specifically at the iPad's browsing history, Scottish Labour deputy leader Jackie Baillie called on Mr Matheson to hand the device over "if he has nothing to hide".
"It's now a matter of integrity," she posted on X, formerly Twitter.
A spokesperson for First Minister Humza Yousaf said the government would "of course" back Mr Matheson if there was to be a confidence vote.
An SNP spokesperson said: "This is simply an attempt to keep a story going, days after Mr Matheson has done the right thing and agreed to foot the bill personally."
Mr Matheson ran up the £11,000 bill during a week-long visit to Morocco with his family around Christmas last year.
The health secretary, who receives receives a yearly salary of £118,511, initially agreed to pay £3,000 towards the bill from his expenses budget.
After the arrangement was reported last week, Mr Yousaf said Mr Matheson did not need to pay back the full sum as it was a "legitimate expense".
But on Friday, Mr Matheson announced he would reimburse the full cost personally.
The bill grew due to the outdated Sim card, which should have been changed after parliament officials agreed a new mobile contract with Vodafone in December 2021.
Sim card warning
Mr Matheson was emailed by officials in February 2022, and it is thought highly likely that he would have also been spoken to by IT staff when he had the Sim card in his mobile phone changed later that year.
Roaming charges are incurred when a mobile device connects to a local network outside of the UK rather than to wi-fi.
The Scottish Parliament said senior officials had accepted assurances that all costs incurred were for parliamentary purposes.
The £11,000 bill is more than the total of all MSPs' mobile phone, business line, tablet and staff phone bill expenses claimed in 2022/23 combined.
The total for all phone-related expenses last year was £9,507.
Michael Matheson said he had paid back his data roaming charges "to put the issue beyond any question whatsoever".
The problem for the health secretary is that there are still quite a few questions outstanding.
Chief among them is how exactly he ran up such a large bill in the first place.
What constituency business was he working on that could amount to £11,000 worth of data?
And if there was any personal browsing mixed in there at all - does that mean he effectively misled the Holyrood authorities to leave the taxpayer footing the bill?
The Tory threat is a hollow one in a way, because the SNP-Green government has a majority, and could vote down any confidence motion.
But even a Holyrood debate would keep the issue among the headlines, and keeps the pressure on Mr Matheson to come up with more comprehensive answers.