Top Brazilian athletes Rafaela Silva and Joanna Maranhao have hit back at racist and sexist insults that have caused Olympic heartbreak and tears.

Rio gold medal judoka Silva, who was called a "monkey" after crashing out of the London Games four years ago, and swimmer Joanna Maranhao, who has had rape threats in recent days, say they will use the hatred to fuel change.

Italian star fencer medal winner Elisa de Francisca made an emotional call for a stand against terrorism and wore the European flag in tribute to the victims of the Paris and Brussels attacks as she collected her silver.

"Europe exists and is united against terrorism. I took the European flag onto the podium for the victims of Paris and Brussels. We cannot let terrorism win," said the 33-year-old after the medal ceremony late Wednesday.

A bus carrying Rio Olympics journalists came under attack Tuesday and police were investigating whether bullets were fired from the notorious City of God favela.

Rio 2016 organisers said two journalists suffered slight injuries in the attack, which set off a new Olympic jitters four days after a bullet hit a Games media centre.

It's too "packaged." There are too many commercial breaks. And key competitions are broadcast with frustrating time delays so they are seen during prime-time.

Welcome to the drama-filled, not entirely live Rio Olympics, NBC-style.

After taking his haul of Olympic gold to an all-time record 21 medals, U.S. legend Michael Phelps returns to the pool on Wednesday in search of further booty.

The Russian authorities and FIFA are concerned over a dispute that has halted construction of a key World Cup 2018 stadium, Sports Minister Vitaly Mutko said Wednesday.

The world record for a transfer fee was shredded Tuesday when French superstar Paul Pogba completed a sensational return to Manchester United from Juventus for 105 million euros ($116 million).

Furious Lebanese judoka Nacif Elias accused Argentine opponent Emmanuel Lucenti of gamesmanship after he was disqualified for an illegal armlock at the Olympics on Tuesday.

Doping tensions in Olympic swimming erupted after American Lilly King beat tainted Russian rival Yulia Efimova and U.S. superstar Michael Phelps demanded life bans for swimmers with a drug record.

A Brazilian judge has ruled that Olympic organizers cannot ban peaceful protests in stadiums, following the controversial expulsion of people holding up signs calling for interim president Michel Temer's resignation.

Rio de Janeiro federal Judge Joao Carneiro Araujo ruled that organizers cannot "prevent peaceful demonstrations of a political nature using the means of placards, shirts or other legal methods in official sites of the Rio 2016 Olympic Games," a spokesman told AFP.