Lebanese judoka Nacif Elias issued an apology after launching into a furious rant following his disqualification at the Rio Olympics on Tuesday.

Brazil-born Elias was thrown out for an illegal joint-lock on Argentina's Emmanuel Lucenti in the preliminary round of the men's -81kg at Carioca Arena 2.

Elias refused to bow and would not leave the mat, then delivered an outburst towards a television camera as he left the arena before returning to apologise for his actions.

His coach was in floods of tears after watching Elias' medal hopes end and the judoka was still at a loss to explain why he had been thrown out, but expressed remorse for his reaction.

"I apologise to the public and to the audience and all the community because of my reaction. This reaction was a tempered reaction, because I have trained very hard for the last four years," said Elias.

"I even trained three times a day, four times a day. I left every training session crying, because I was very compelled to win the gold medal.

"I don't understand why I was disqualified, but I accept what the judge has said.

"I am very concerned about this example that I have given for the children. I apologise to them and I'm very concerned to give a good example to the children, which are the future of judo."

He added: "I was very confident of the gold medal because I had beaten the Argentinian [Lucenti] twice, the Canadian [potential next opponent Antoine Valois Fortier] twice in the world championship, so I was very confident to win the gold medal."