Pakistan, who will play their quarter-final against Australia in Adelaide on Friday (March 20), will be without the services of Irfan.
"Pakistan pacer Mohammad Irfan underwent an MRI scan on Monday afternoon and the radiologist's report showed a stress injury of the pelvis but was inconclusive," a report on International Cricket Council's (ICC) website said on Tuesday.
Pakistan's physiotherapist Brad Robinson ordered a more detailed scan, which was carried out Tuesday afternoon, and it reconfirmed an obvious stress fracture in the pelvis, it added.
"This injury rules Irfan out of the World Cup," said Brad Robinson.
The Team Pakistan think tank is not immediately asking the selection committee back home for a replacement, but shall wait until the result of the Friday's quarter-final encounter against Australia to do so, the report added.