Usain Bolt says he will only compete at the World Championships in London two years from now if he has the motivation to add to his impressive medal collection.

Bolt was part of Jamaica's successful 4x100 metres relay team on Saturday, adding to his individual 100m and 200m golds in Beijing.

There remains doubt as to whether the charismatic sprinter will seek to add to his 11 world golds in 2017 and Bolt suggested he would not make a decision until after the Olympics in Rio de Janeiro next year.

The 29-year-old will seek to win gold in three events for the third Games running and told reporters: "If I can find some reason to motivate myself one more time, I'll definitely come to London.

"I asked Michael Johnson one time, why didn't he continue in the sport, why did he stop running so early when he was on top, and he said 'I have done everything that I want to'. 

"So I think going to Rio and winning those three gold medals and breaking more records, after that it is going to be hard to motivate myself to continue."

Bolt claimed victories over Justin Gatlin in the 100m and 200m - the results deemed by many to represent positive news for athletics due to the American having previously served two bans for doping.

Gatlin's United States team were then disqualified in the relay final following a clumsy final handover between Tyson Gay and Mike Rodgers.

And Bolt was again quizzed over his personal relationship with Gatlin.

"I wouldn't say we are mates, let's not say that. We're cool because we are competitors and he is cool after the championships so we do exchange words, I wouldn't use the word mate, but he is a cool person," added the Jamaican.

"[To win three golds] means a lot, I came out here to win three golds that was my aim, I told you guys.

"A lot of you guys [in the media] had doubts but I got it done so I am happy about it.

"It's been a beautiful championships, I'm really happy. I came here to win three gold medals, after all the doubts that people have had through the season, all the injuries that I have been through, and I got it done."