HONG KONG (Reuters) - China's government and official sporting bodies have condemned fans for using social media to attack and spread rumours about the country's Olympians and said the behaviour had an extremely negative impact on athletes, coaches and their families.

China's Ministry of Public Security said it would crack down on "illegal and criminal acts of 'fan circles' as part of its internet security measures" and urged people not to "spread rumours, attack and slander others".

The bureau highlighted four cases where it had taken action against fan groups for their treatment of athletes who competed at the Paris Olympics, including some fans who had "insulted and defamed table tennis players and coaches".

China's table tennis association said the "chaos" of fan groups had interfered with the team's training and competition.

At the weekend, the Chinese Gymnastics Association said athletes, coaches and managers had been the targets of rumours and insults, negatively impacting the work, life and family of relevant personnel.

The statements came after swimmer Pan Zhanle, 20, who broke the world record in the 100 metres freestyle, disbanded his only fan group page on social medial platform Weibo and told state broadcaster CCTV that he preferred to keep a low profile.

"A bad thing about being famous is that too many people surround me," he said. "I'd rather not have as much success if it meant I could continue training hard with peace of mind."

The 40 golds were an all time high for a Games outside China and was achieved despite immense pressure and tightened scrutiny resulting from a doping row involving some of its swimmers.

(Reporting by Farah Master and the Beijing newsroom; Editing by Peter Rutherford)