RIO DE JANEIRO (AFP) - Alistair and Jonny Brownlee became the first British brothers to win gold and silver at an Olympics on Thursday when they blitzed the field to win the men's triathlon in Rio de Janeiro.

The siblings from the northern county of Yorkshire were separated by Spain's Javier Gomez on the London 2012 Olympic podium but they were not to be denied a 1-2 in hot conditions at Copacabana beach.

The Brownlees finished in the first group of swimmers and pushed hard in the first kilometres of the hilly bike race before opening up an unbridgeable gap in the 10km run.

Alistair, 28, then accelerated in front of his brother with 3km to go before grabbing flags, slowing down and walking over the line, with Jonny, 26, six seconds behind.

Alistair became the first triathlete to win back-to-back Olympic golds while both Brownlees are the first in the sport to medal at consecutive Games.

The brothers collapsed in exhaustion after crossing the line and completing a victory made all the sweeter by their injury struggles of recent years.

"Today we knew that if it went right we could (win gold and silver)," said Alistair. "When that gap went up to a minute... we both knew that was going to be the outcome."

Jonny said: "When we crossed that finish line I was pretty emotional. 'We've done it!' I said to Alistair, because we had done it.

"Triathlon is one of those sports where lots can go wrong. We had a terrible year last year... lots of people said we had no chance. So that makes it even more special."