RIO DE JANEIRO (Reuters) - Rio will be the last Olympics for 2012 double gold medallist Yannick Agnel after the French swimmer failed to defend his 200m freestyle title on Sunday and announced his imminent retirement.

"This is my last international competition," the 24-year-old told French media after finishing 19th overall in Sunday's preliminary heats with only the top 16 going through to the semi-finals.

"If I continue four years like the past four years, you will find me between four planks."

Agnel won gold in both the individual 200m and 4x100m relay in London four years ago as well as a silver in the 4x200m. He has still to compete in the latter relay in Rio but has no more individual events.

His place at the Olympics had been in doubt earlier in the year when he came third behind Jeremy Stravius and Jordan Pothain in the French trials after failing to touch the finishing pad correctly.

Only the first two qualified but Pothain provided an opening by deciding to enter the 400m freestyle instead.

"I am disappointed, very disappointed," he said of his performance on Sunday. "But I gave everything, I really did my maximum today. I did everything I could.

"It was already a victory in itself to be here, to show everybody that despite everything I could change my luck and be competitive. That's what I tried today and even if it didn't happen, I'm happy to be here and have tried to defend my title," said the swimmer, who also won two golds at the 2013 world championships.

Agnel missed last year's world championships in Russia due to a lung infection.

His London 2012 winning time makes him still the third fastest swimmer of all time in the 200m freestyle behind Michael Phelps of the United States and German world record holder Paul Biedermann. His time of 1 min 43.14sec remains the fastest in a textile suit.