By Justin Palmer

LONDON (Reuters) - Russian Natalya Antyukh, a late starter to jumping barriers, secured the Olympic women's 400 meters hurdles gold medal on Wednesday and said she would put retirement on hold to think about a world record attempt.

The 31-year-old Antyukh, who only switched to hurdling three years ago after running the flat 400, dug deep to hold off American Lashinda Demus and win in a lifetime best of 52.70 seconds.

"I was going to finish my career here but now I will think about it - maybe not," Antyukh, who won Olympic 400 bronze in 2004, told reporters.

"I have done a lot of work, to get a personal best is amazing - a world record soon would be great. It's not very far away."

Compatriot Yuliya Pechonkina's world record of 52.34 has stood since 2003.

Antyukh, whose switch to hurdling almost paid immediate dividends when she won the European title in 2010, and world champion Demus both raced hard from the gun, with the Russian just having the edge rounding the final bend.

Demus tried valiantly to close in the home straight but Antyukh battled on to take gold by seven hundredths of a second, although she was not sure she had won.

"I felt Demus very close to me on my right hand. I couldn't have imagine winning this race and I did not understand at the end that I was the winner because I felt Demus had caught me," she said.

Irina Privalova was the last Russian 400 hurdler to win Olympic gold when she triumphed in Sydney in 2000.

Antyukh is fairly certain she will not be in Rio de Janeiro to defend her title in 2016.

"I will try for another life. I want a family...I want children," she said.

Czech Zuzana Hejnova won bronze in 53.38.

(Editing by Ed Osmond)