Swimming legend Ian Thorpe has had his say on Luke Greenbank's heartbreaking Olympic disqualification.

The Cumbrian star won his men's 200m backstroke heat in style - only to be kicked out for falling foul of a 15m underwater rule.

Greenbank was submerged for more than 15m of his final length in Wednesday's heat in Paris's La Defense Arena.

The Cockermouth swimmer was crestfallen when learning of his disqualification as his medal hopes lay in tatters.

Pundits have given their assessment of what happened with Australia's multiple Olympic champion Thorpe claiming there was "no need" for Greenbank to have gone past the 15m mark.

“And it wasn’t just a little bit, it was a significant amount past [the mark],” Thorpe told Australian broadcaster Nine.

“That is well past that mark and there is no need for that in a 200 metres.

"Perhaps in a 50-metre race you might take the chance, but in a 200 metres there is no benefit.

“You can see how devastated he is after the race.”

Greenbank, who started out at Cockermouth Swimming Club, said he was “absolutely gutted” with the outcome.

The full 15-m rule - which applies in backstroke, butterfly and freestyle  events - says: "It shall be permissible for a swimmer to be completely submerged for a distance of not more than 15 metres after the start and after each turn.

"By that point, the head must have broken the surface. The swimmer must remain on the surface until the next turn or finish."

Greenbank was a double medallist at the previous Games in Tokyo and his time in the Paris heats was the fastest of all the competitors.

There will be no Team GB swimmers in tonight's 200m backstroke final after Oliver Morgan, who was also in Greenbank's heat, missed out in the semi-finals.