The 22-year-old from Sheffield has been troubled by the injury for a few weeks and was forced to withdraw after the first day's action at the IAAF World Challenge Hypo Meeting in Gotzis on Saturday when the problem flared up during the high jump.

The Commonwealth Games bronze medallist, who was lying second at the time after completing her four disciplines, pulled out as a precautionary measure.

The multi-eventer, who missed out on the World Championship bronze medal by only 41 points behind team-mate Kelly Sotherton last August, had CT and MRI scans at the Olympic Medical Institute yesterday, where a fracture was revealed.

As yet it is unclear whether the break occurred in competition or earlier in training and Ennis, who is based at the English Institute of Sport in her home city, will embark on an immediate rehabilitation programme.

The scan revealed three fractures to the joint, which had been troubling her in recent weeks, although not seriously enough to prevent her competing in several early-season meetings.

Ennis rushed home from Gotzis in Austria on Sunday morning, very anxious to discover how serious the injury was and her worst fears were revealed after her scan.

Last night she was trying to come to terms with the shock news, and said: "I'm obviously upset with the results and I'm gutted to be missing out on my first Olympics, but injury is part of life as a heptathlete.

"I am determined to make a full and speedy recovery from this and enjoy a long athletics career."

UK Athletics performance director Dave Collins said: "This is nothing but terrible luck and is a sickening blow for Jess. Obviously with the Olympic Games just a matter of weeks away, the timing could not have been more cruel."

Her coach Toni Minichiello said: "I'm deeply, deeply disappointed by what the scans have shown us. There was nothing in Jessica's training or in her PB (personal best) performances that we've seen over the last few weeks to indicate that an injury of this nature was present."