Olympic heptathlon champion Jessica Ennis-Hill has pulled out of the world athletics championships in Moscow because of an injury. 

Ennis-Hill has been struggling with an Achilles injury but returned to compete in the Anniversary Games at London's Olympic Stadium over the weekend.

However, the British star finished a disappointing fourth in the 100-meter hurdles and eighth in the long jump.

"Up until now we have been focusing on managing the pain so I can train and get myself in shape to go out there to win in Moscow - which has meant not focusing on finding a cure for the injury,'' Ennis-Hill said in a statement.

No athlete likes to miss the opportunity to compete at a major Championships - they don't come round that often

Jessica Ennis-Hill, Olympic heptathlon champion

"The time has now come to stop chasing fitness and look to cure the problem.

"I am so glad I got to compete in London last weekend as it gave me a clear picture of where I am - and it is definitely not where I want to be both regarding pain and also form. To say I am gutted is an understatement - no athlete likes to miss the opportunity to compete at a major Championships - they don't come round that often.''

The 27-year-old Ennis-Hill was looking to regain the world title she lost to Tatyana Chernova of Russia in 2011. Chernova has also withdrawn with an injury.

"It's not been the easiest or simplest of decisions," coach Toni Minichiello said.

"The pain management did improve, and Jessica was able to compete in London, but the next few days have not seen enough improvement that would have made completing the two-day, seven events of the heptathlon possible."

Ennis-Hill is not the first champion to withdraw from the event with Kenyan 800m runner David Rudisha losing the race to recover from injury and Asafa Powell and Tyson Gay being found positive for doping.  

Reigning 100 metres champion Yohan Blake has also withdrawn because of a hamstring injury.

Source: AP