Christine Ohuruogu
Ohuruogu\'s beat Amantle Montsho in a photo finish to seal her win. (Reuters)

Great Britain's Christine Ohuruogu claimed her second World Championship title after sealing an extraordinary victory to win gold in the 400m in Moscow.

The 29-year-old completed a late charge to beat reigning champion Amantle Montsho by four thousands of a second finishing with a time of 49.41, a new British record.

Montsho took an early lead with Ohuruogu left with a seemingly impossible task of gaining ground on the Botswana-born favourite as they approached the final bend. A stunning late burst from the Brit however saw her claw back ground as the pair approached the finishing line.

A photo finish was necessary to decide the evening's winner but Montsho's failure to dip at the line saw Ohuruogu credited with the win by the finest of margins, crossing the line in 49.404 ahead of her rivals effort of 49.408, a time which has broken Kathy Cook's national record which has stood for 29 years.

"I can't believe I've done that, it feels like a dream. It is what I have been working towards all season, it wa so tight on the line and I was so desperate to win it. I just wanted my name to come up," Ohuruogu said.

"I was thinking do what you can, just get over the line. The icing on the cake is the national record, that's all I wanted."

Ohuruogu's victory saw her become the first British woman to claim two World Championship titles, adding to her 2007 gold medal success in Osaka where she was also forced to come from behind to seal victory.

"(As I was running for the line) I just remember thinking 'my coach is going to kill me," Ohuruogu told BBC Sport.

"He gave me instructions but I never listen. But I never panic. The race isn't won until you cross the line, I knew it was going to be tight.

"I didn't know how far behind I was, but I knew in the last 50m the others would start dying and when I crossed the line I just thanked God I had finished.

"We didn't know what was happening, I heard the crowd screaming and was thinking 'do I really want to see what happened?'"