Former Newcastle United midfielder Cheick Tiote has died aged 30 after collapsing during training in China.
In his seven years at United the Ivory Coast player made over 150 appearances, including three last season.
He joined Chinese second-tier side Beijing Enterprises from Newcastle in February.
"It is with deep sadness I confirm that Cheick Tiote sadly passed away earlier today after collapsing in training," said spokesman Emanuele Palladino.
"We cannot say any more at the moment and we request that his family's privacy be respected at this difficult time. We ask for all your prayers."
Born in the Ivory Coast, Tiote was part of the Ivorian squad that won the 2015 Africa Cup of Nations.
He began his professional career in Belgium with Anderlecht in 2005 before moving to Dutch side FC Twente, where he made 86 appearances and won the Eredivisie league title in the 2009-10 season under manager Steve McClaren.
Tiote, a defensive midfielder, then signed for Newcastle in 2010 for £3.5m.
In February 2011, he scored a memorable goal as Newcastle United came back from 4-0 down to draw with Arsenal in the Premier League.
He joined Beijing Enterprises Group FC for an undisclosed fee in February 2017.
'A true professional and above all a great man'
A statement from Newcastle said: "We are devastated to have learnt of the tragic passing of Cheick Tiote at the age of just 30.
"The thoughts of everyone at Newcastle United are with Cheick's family, friends, team-mates and everyone connected with the clubs he represented."
Newcastle manager Rafa Benitez said: "It is with great sadness that I have this afternoon learned of Cheick's death.
"In all the time that I have known him, he was a true professional, dedicated and above all, a great man. Our hearts go out to his family and friends at such a sad time."
'His smile lit up the room'
His former manager at both Twente and Newcastle Steve McClaren described him as the 'toughest player' he had ever seen.
"He had the most beautiful smile in football. Every morning at Newcastle if (Papiss) Cisse and Cheike were smiling I knew the world was OK," he told BBC Radio 5 live.
"I knew him first as a young player at Twente. He was the toughest player I've ever seen. On the field and in training he was such a competitor. He wanted to win every game, kick every player and win every tackle.
"He was the kind of player that everyone wants in their team. He was a winner. I just can't believe it.
"It was his dream to play in China and I was so delighted for him when it happened. He earned money to look after his family. He loved playing football to look after his family. All the relatives, uncles, aunts, grandparents, they all relied on him to look after them."
"Cheick was one of the best we had in terms of his attitude," Newcastle legend Peter Beardsley told BBC Radio 5 live.
"He had a wicked sense of humour, he was top class and he will certainly be missed in this city."
Beardsley, who is still on the staff at Newcastle, added: "He was flat out every day in training and was a brilliant example to the kids at our club. He loved a tackle - he wasn't horrible, but very aggressive. Every time he saw the ball he went for it.
"He was also really funny in the dressing room. He had a brilliant smile and he lit up a room when he smiled. He was fantastic.
On Tiote's goal against Arsenal, Beardsley added: "It was an unbelievable volley and it couldn't have happened to a nicer person.
"I can still see him running up the end of the pitch. He must have run 70 metres to celebrate with the fans."
Tributes on social media
Former Newcastle goalkeeper Steve Harper posted: "Gutted to hear the awful news about my former teammate Cheick Tiote today. Thoughts with his friends and family."
Manchester City captain Vincent Kompany, who played with Tiote at Anderlecht, tweeted: "I am speechless and so incredibly sad. Cheick Tioté was one of the nicest and toughest teammates I have ever had. Rest in peace brother."
Former Newcastle and current Stoke City goalkeeper Shay Given said on Twitter: "Shocked & saddened to hear of the passing of Cheick Tioté, I pass on my condolences to his friends & family, way too young."
Papiss Cisse, who played with Tiote from 2012-2014 at Newcastle, tweeted: "Goodnight brother, You will be missed. My heart goes out to his family. Gone too soon."
Newcastle midfielder Siem de Jong said: "Terrible news, R.I.P. Tiote. Always enjoyed sitting next to you in the dressing room my friend."
Match of the day commentator Gary Lineker said on Twitter: "Dreadful news that Cheick Tiote has passed away. So young. So tragic."