She won the world championships in 2005 and a fit Paula would clearly be in contention to regain that title, but she has taken that difficult decision and we have to respect that.'

Radcliffe, 35, holds the world record over the 42.195-kilometres distance with 2:15:25 at the 2003 London Marathon.

However, she has always struggled at championships, with a 2005 worlds gold her only title. She has a 10,000m silver as well from 1999.

Radcliffe did not compete at the 2008 worlds and had to settle for 23rd in the Beijing Olympics marathon last year over injury problems.

'Running in New York this weekend was a necessary part of the process to ascertain my race fitness and after speaking with my coaching and medical team, I knew I was sadly just not quite ready,' she said.