Newly-crowned World Champion Casey Stoner has said the death of Marco Simoncelli at the age of 24 is sickening and he is shocked and saddened by the passing of his HRC colleague.

Simoncelli died earlier today from head, neck and cheast injuries following an accident on lap two of the Sepang MotoGP. He was taken to the circuit medical centre but succumbed to his injuries. His team said simply: "CIAO "SUPER SIC"

"I'm so shocked and saddened by the loss of Marco. When things like this happen it reminds you how precious life is, it makes me feel sick inside. All I can say is how sorry I am for Marco's whole family I can't imagine what they are all going through and our thoughts and wishes are with them at this time. I hope they all stay close and pull through this tragedy together," said Stoner.

Team-mate Dani Pedrosa added: "In a tragedy like this there is not much to say. I just want to give my condolences to his family and all the people who love him. I've been with his father and all we could do was to hug, nothing else matters. It was a fatal accident and everybody in the paddock remains in shock. Many times we ourselves forget how dangerous this sport can be and when you lose people on the way nothing has any meaning. It's clear that we all do what we like, what we love, but on days like today nothing matters."

Fellow Italian Andrea Dovizioso said: "In these circumstances, words don’t seem to be appropriate. I think of Marco’s family and all the people dear to him, in particular his father and mother. I also have a child and what happened today is the hardest situation you can imagine. I watched the images and I’m shocked: in a race you fight and push hard and disaster is often around the corner. Marco was a strong rider and he always pushed hard. We raced together since we were kids, I saw him always pushing to the maximum, he crashed many times, but without major injuries, he was seemed invincible. What happened today seems impossible."

Shuhei Nakamoto, HRC Executive Vice President: "I just don't know what to say, words escape me. Marco was a very nice guy and a very talented rider. Sometimes I was a little harsh with him, for example after his first MotoGP podium in Brno when I told him: 'Lucky podium!' and he was so angry... but I wanted to motivate him as I knew he was able to do even more. I was thinking that when he won his first race we would have been able to celebrate together... Now I just want to say thank you to Marco, for what you gave me and pass my sincere condolences to his family and this very sad time."

Hector Barbera added: "I am in shock. We are bike riders and we are aware that there are risks involved with what we do, but we also know that every day our safety is looked after more and more by the organisers. These past few years have seen a huge amount of work done to try and make our job even safer. Despite this, there are moments in which misfortune can lead to tragedy -and we saw this happen today with Marco Simoncelli. Today is another tough day for motorcycle racing. We have lost a great companion, and I will remember Marco as a great rival with whom had some fantastic battles in the past."

Jorge Lorenzo Tweeted: "On a day like this I don't know what to say. Marco, rest in peace."

Ben Spies Tweeted simply: "Super Sic rest easy"

Nicky Hayden Tweeted: "Sometimes life just don't make sense... RIP #58 your were a star on & off track we all going to miss you…"

Cal Crutchlow Tweeted: "RIP Marco Simoncelli ! A great rider and all round nice guy. My thoughts are with all his family & friends. I will never forget today … #58."

Eugene Laverty Tweeted: "Devastated to hear of the death of Marco Simoncelli, one of the best of our generation. Thoughts go out to his family. RIP Marco"

Former team-mate and World Supersport Champion Chaz Davies: "I was fortunate enough to be team mate to Marco in 2002. He was a genuinely fun guy and taught me my first unrepeatable Italian!"

The Marlboro Ducati team issued this statement: "Ducati, its team and its riders are deeply affected by the tragedy that struck the MotoGP world today, and they gather around the family, friends and team of Marco Simoncelli, who lost his life in a terrible accident during the Malaysian Grand Prix.

"We will always remember Marco for his smile, his enthusiasm, his big heart and for the incredible emotions he allowed us to experience in recent years. He was one of us."

Tech3 Monster Yamaha said: "The Monster Yamaha Tech 3 Team and Tech 3 Racing Moto2 team extends its deepest condolences to the family, friends, and colleagues of Marco Simoncelli, who succumbed to injuries he received in this afternoon's Malaysian Grand Prix.

"Monster Yamaha Tech 3 rider Colin Edwards was involved in the second lap incident and he suffered a dislocated left shoulder. The American has left the Sepang International Circuit to begin his recovery at home in America and his thoughts and prayers are with Simoncelli and the Gresini Honda family.

"RIP Super Sic  - A much-loved star on and off the track."

Rizla Suzuki said: "All at Rizla Suzuki are deeply affected by today’s tragic events and send their deepest condolences to Marco’s family and friends during this time of great loss. R.I.P Marco Simoncelli, 20 January 1987 – 23 October 2011. A true competitor."

Legendary rider and team boss Jorge Martínez 'Aspar': "What has happened today is immensely sad. It should be said that every Friday before a Grand Prix, the Safety Commission convenes at 5pm with all the MotoGP riders to evaluate safety issues at all Grand Prix circuits. Marco lost the front end and attempted to save the crash, but unfortunately the inertia of the bike took him onto the inside of the corner just when Edwards and Valentino were passing. There was nothing that they could do to avoid him. Today is a tremendously sad day for the entire paddock and for those who love motorcycle racing."

Taka Horio, general manager Bridgestone Motorsport Department, said: “Today we are left devastated. Our thoughts and prayers are with Marco’s family at this terrible, terrible time, and with his team. Words can do no justice to the emotion we are all feeling.

"The MotoGP family has lost one of its bright stars, a genuine character whose larger-than-life persona, charisma and unstoppable spirit were infectious, and we’ve all lost a great friend. We worked closely with Marco for his first two years in MotoGP and it was clear that he was a true racer, something he proved again and again this season.

"Determined to the end, and a great showman. His ascent through the field in just two seasons has been fantastic to watch, testament to his raw talent, ability and dedication to the sport he so loved. We remember fondly the tenacity and spirit with which he raced, and he will be sorely, sorely missed.”