London:England all-rounder Andrew Flintoff has suffered a deep vein thrombosis in his right calf following knee surgery, a statement issued on Sunday by the England and Wales Cricket Board (ECB) said.
The 31-year-old underwent an operation after retiring from Test cricket following England's 2-1 Ashes series win over Australia.
Flintoff, who has said he wants to continue his one-day international career, is expected to be out of action for at least six months.
"Andrew Flintoff recently suffered a common complication of surgery, a minor deep vein thrombosis in his right calf," the ECB statement said.
"This will require a simple course of treatment and will not complicate his recovery from surgery."
Fast bowler and hard-hitting batsman Flintoff's career has been blighted by a succession of injuries.
England captain Andrew Strauss, speaking after England had lost the second one-day international against Australia by 39 runs here at Lord's on Sunday to go 2-0 down in the seven-match series, said: "You don't want any complications, an operation like that is a big enough tribulation as it is.
"I just feel for him because he's got a lot of rehab ahead of him, and you don't want it to be slowed down in any way. Hopefully, it all will all go according to plan from here on."