LONDON (Reuters) - World marathon record holder Paula Radcliffe said on Thursday she had a stress fracture of the femur and that some specialists had told her it would be impossible for her to compete in the Beijing Olympics.

The 34-year-old, who made the announcement via a teleconference, said she was "not giving up on the Olympics" but would only go if she felt competitive.

"It's not good news and not the news I wanted to hear, but I will give myself every chance," said Radcliffe, who originally thought she had a hip muscle injury.

"But I won't run through pain and I won't go if I feel I can't be competitive. It's not ideal but I'm trying to stay positive."

(Reporting by Martyn Herman, editing by Trevor Huggins)