Usain Bolt has blasted into athletics immortality with gold in the 200m final at the London Olympics.

In a Jamaican clean-sweep, Bolt blasted clear from the start to push Yohan Blake and Warren Weir into the minor medals to become the first man to win back-to-back Olympic sprint titles.

Bolt's winning time of 19.32 seconds was outside his world record. Blake was second in 19.44 and Weir third in 19.84.

Bolt, the two-time 100m champion, is now the first man with two Olympic titles in the 200, part of his oft-stated goal of becoming a "living legend" in London.

Four years ago, he went 3 for 3, winning the 100, 200 and 4x100 relay, all in world-record time. He went on to break his marks in the two individual races at the 2009 world championships - records that still stand, 9.58 in the 100 and 19.19 in the 200.