Full-backs Alan Hutton and Lee Wallace have withdrawn from the Scotland squad, along with striker Chris Martin.
Scotland play Italy in Malta on Sunday, with another friendly against Euro 2016 hosts France on the following weekend.
The Scottish FA has given no further details on the trio pulling out and no replacements have been named yet.
Last week, Scott Fox, Jack Hamilton, Stephen Kingsley and Craig Bryson were drafted in to cover for absent players.
Barry Bannan, Robert Snodgrass, Shaun Maloney, Andrew Robertson and Allan McGregor are all involved in the English Championship play-off final the day before the game against Italy, while Dundee goalkeeper Scott Bain has a back problem.
Rangers captain Wallace was returning to the squad after a long absence, having last been capped in November 2013.
Aston Villa’s Hutton made his 50th international appearance in the 1-0 win over Czech Republic in March, while Derby forward Martin has scored once in eight matches for Gordon Strachan’s side.