The 7 feet 1 inch tall left-armer has bagged 8 wickets in 5 games for the Misbah-ul-Haq-led side but missed the team's last league game against Ireland.
"A more detailed scan ordered by team physiotherapist Brad Johnson on Tuesday and it confirms an obvious stress fracture in the pelvis," the PCB statement said.
"The injury rules Irfan out of the World Cup," Johnson said in the statement.
Irfan, alongwith fellow left-arm pacers Wahab Riaz and Ehsan Adil, shared 3 wickets apiece in the crucial league win against the mighty South Africans which put their their campaign back on track after losing the first couple of games against India and West Indies.
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In a game pitted to be a battle between the left-armers, 3 each from Pakistan and Australia, Irfan's absence may hurt the 1992 champions against the co-hosts at the Adelaide Oval.
The Pakistan team management is expected to fly in a replacement for Irfan only if the Men in Green advance to the semi-finals of the 50-over showpiece event.
Irfan, 32, has coped with fitness problems throughout his career and since he made a comeback to the national team in late 2012. He had to miss out on cricket for nearly 10 months after he suffered a hip injury during a Twenty20 match against South Africa in Dubai in November last year.