The death of Sunderland fan and England striker Jermain Defoe's 'best mate' Bradley Lowery aged six after a courageous battle with cancer on Friday drew an enormous outpouring of reaction on Twitter.

Here AFP Sports picks out some of the tributes.

"The thoughts of all at #SAFC are with the Lowery family following this afternoon's sad news. #OneBradleyLowery (blue heart emoji)." -- Sunderland.

"There's only one Bradley Lowery." -- England team tweet with a photo of Lowery at the 2018 World Cup qualifier with Lithuania wearing an England strip giving the thumbs up sign and Defoe's hands on his shoulders.

"Today, the football world lost one of its bravest fans. Rest in peace, Bradley Lowery." -- football's world governing body FIFA.

"Terribly sad to hear that little Bradley Lowery has passed away. A warrior and an inspiration to the end. RIP Bradley." -- Former Barcelona and England striker turned TV presenter Gary Lineker.

"We are sad to hear of the passing of Bradley Lowery, whose bravery touched the hearts of football fans around the world. #OneBradleyLowery." -- The Premier League with a photo of an emotional Defoe holding a smiling Lowery, as ever dressed in a Sunderland top.

"You inspired us all with your bravery. Rest in peace, Bradley Lowery." -- West Ham United.

"My thoughts and prayers are with Bradley and his family, your beaming smile will never be forgotten nor your amazing strength to fight (emoji of hands clasped in prayer)." -- Britain's former heavyweight world boxing champion Frank Bruno.

"Such sad news about @Bradleysfight, sending all my love to his friends & family!! Goodnight godbless little man (broken black heart emoji and four kisses)." -- England women's football star and Barcelona-bound Toni Duggan.

"All at Chelsea are deeply saddened to learn of Bradley Lowery's passing. He touched all of us with his bravery and winning smile." -- English champions Chelsea tweet with photo of several players including captain Gary Cahill and Cesc Fabregas surrounding Lowery with the former holding a Chelsea shirt in front of the youngster... Who is nevertheless dressed in his usual Sunderland strip.

"He touched all of our hearts. Rest in peace, @Bradleysfight." -- Swansea City.

"Your bravery and strength was a true inspiration to us all. Rest in peace, Bradley. (black heart emoji)." -- Tottenham Hotspur.

"So sad to hear the news of @Bradleysfight passing but what an incredibly tough and inspirational person (emojis of sad face, broken heart and crying person)." -- Stoke City and England goalkeeper Jack Butland.

"The thoughts of everyone at #afcb are with the Lowery family and their friends at this difficult time. #OneBradleyLowery (red and black heart emojis)." -- Bournemouth, where Defoe is now playing.