They come after a school canteen and Holyrood itself were drawn into the scandal.
It emerged on Saturday that catering giant Sodexo, which withdrew beef from its UK sites after a frozen product tested positive for horse DNA, had supplied burgers to the Parliament.
A spokeswoman said that, while written assurance had been received from Sodexo that supplies to Holyrood are not affected, its beef burgers have been taken off the menu there as a "precautionary measure".
It came a day after Scottish councils were told not to use any frozen beef products following the discovery of horse DNA in a canteen burger at Cumbernauld High School.
Scottish Conservative leader Ruth Davidson called for Richard Lochhead, the Environment and Rural Affairs, to make a fresh statement to parliament in light of the news.
Ms Davidson said: "Richard Lochhead is clearly out of his depth in dealing with this crisis and is rapidly running out of time to bring it under control.
"This issue has now gone straight to the heart of the Scottish Government.
"Now, we know when he stood up in Parliament last week he was less than straight when he talked about the quality of food being served in our schools. With every day that passes, it's becoming more apparent that Richard Lochhead has no idea how widespread this food scandal is."
Meanwhile, leading microbiologist and food expert Professor Hugh Pennington said consumers were safer eating horse meat than beef because there was no risk of developing the killer E.coli bug.