Olympic 400m and 1500m freestyle champion Sun Yang has apologised to long-term coach Zhu Zhigen after disagreement between them led to the swimmer requesting a replacement for his mentor. The partners started to work together again today.

Zhu had guided Sun for 10 years, since the swimmer was 12, until the row over commitment and extracurricular activities blew up. Sun has now posted a photo of himself hugging Zhu on his blog to show that the two have made up.

Li Jianshe, president of the Zhejiang College of Sport, with which Sun and Zhu are affiliated, confirmed that Sun is back at the pool under Zhu's guidance. "Yes, they have already reconciled and will continue working together. Sun will return to the training pool on Monday," Li told the China Daily.

Zhu voiced his disapproval of the freestyle star's budding romance with a flight attendant last month and questioned his charge's commitment to retaining his 1500m world crown in Barcelona this summer. Sun responded by asking the college to replace Zhu.

However, the college punished Sun instead, withholding a month of Sun's stipend and suspending him from any commercial activity.

Sun said that he had "felt too embarrassed to say sorry" until this weekend past, according to Shang Xiutang, director of the national swimming administrative centre.

"He knew he did something wrong, but took a while to clear his mind and get ready to apologize to Zhu," Shang told the Chinese media. "Sun told me he knew it was impossible for him to split with coach Zhu and he understood Zhu criticized him for his own good. They will start over soon."

On whether the governing body will stop Sun from dating his girlfriend, Shang said: "He's the Olympic champion, who has great social influence. Practicing to keep his form is his priority so we are in objection to his dating during training. But if their relationship is established, it's inappropriate to force them apart. Our requirement of him now is to concentrate on his training and follow all the team's rules."

Sun is scheduled to compete at the national championships and world championship trials from April 1 in Zhengzhou, Henan province. The meet also serves as selection trials for the National Games in September.