England team faces a big setback in the World Cup
Roy, who suffered the injury while fielding during England's win over the West Indies on Friday, has been ruled out of Tuesday´s group fixture against Afghanistan at Old Trafford and Friday´s match against Sri Lanka at Headingley.
Meanwhile, England captain Eoin Morgan, who suffered a back spasm in the field against the West Indies, and like Roy did not bat in that match, will be assessed ahead of the Afghanistan clash and could yet play against the tournament minnows.
"England batsman Jason Roy, who left the field during West Indies' innings in the ICC Cricket World Cup fixture on Friday due to left hamstring tightness, underwent an MRI scan on Saturday in London," an ECB statement read.
"The MRI confirmed that Roy has suffered a hamstring tear. As a result of the injury, he will be reassessed on an ongoing basis this week.
"He is set to miss England's next two matches in the ICC Cricket World Cup against Afghanistan (18 June) and Sri Lanka (21 June)."
As for Morgan's condition, the ECB said he had undergone a scan at the weekend and received further treatment.
"The spasm has settled down and will be monitored over the next 24 hours ahead of England's next match against Afghanistan tomorrow (Tuesday) at Old Trafford, Manchester," the statement added.
Roy, who suffered a hamstring injury during England's tour of the Caribbean earlier this year, hit a fifty in their World Cup opening win over South Africa and then struck a commanding 153 in a victory over Bangladesh.
But he fell for just 14 during England's surprise group loss to Pakistan at Trent Bridge.
Joe Root was promoted to open alongside Jonny Bairstow against the West Indies and the Test skipper responded with an unbeaten century. -APP/AFP