Then Chinese vice-president Xi Jinping receives a Los Angeles Lakers jersey signed by Kobe Bryant and a jersey with David Beckham's signature. Beckham (left) and Lakers star Johnson (right) presented the jerseys when Xi was watching an NBA basketball game in Los Angeles during his visit to the US on Feb 17, 2012. [Xinhua]

Chinese leaders' interest and even participation in sports has emerged as a way to strengthen relations between China and other countries, sports sociology experts say.

China's sports-diplomacy tradition shone again over the weekend, after Premier Li Keqiang's remarks on the UEFA Champions League final during his visit to Germany made headlines.

Media in China and Germany reported on Monday that Li expressed his congratulations to Germany after watching the final between two German clubs, Bayern Munich and Borussia Dortmund, on television in Berlin on Saturday.

Pundits believe showing Li's interest in soccer during his visit will help strengthen ties between the two countries.

"It was necessary to let the world know that he was also a fan of such a highly anticipated game in Germany on the night he arrived. It worked well to close the distance between the two countries' peoples," Lu Yuanzhen, a renowned sports sociologist with South China Normal University, said on Monday.

According to China News Service, Li said it was too hard to predict the eventual winner on the night of the final, but said after the game that it was a victory for German soccer. He also called on all friends of Germany to cheer for the achievement together. Lu said Li deserves credit for his remarks.

"It showed that the Chinese are also interested in what concerns Germans in the sports scene, which could establish a foundation for the two sides to talk, either on the state level or grassroots level.

"Starting formal diplomatic talks on big issues with sports topics is a safe and smart move, which helps them find something in common," Lu said.

Attending sports events has been a popular activity on the schedule of Chinese leaders' overseas tours. President Xi Jinping wrapped up his US visit last year by watching a live NBA game at the Staples Center in Los Angeles.

Accompanied by Los Angeles Mayor Antonio Villaraigosa, Xi, vice-president at the time, watched part of the fourth quarter of a regular season game between the Los Angeles Lakers and Phoenix Suns before he was presented with a jersey with his name on it in front of NBA legend Magic Johnson and soccer star David Beckham.

Xi voiced his enthusiasm for US basketball, saying that he sometimes watches NBA games on television. After visiting the US, Xi showed his sports skills by kicking a football and swinging a hockey stick during a visit to Croke Park Stadium in Dublin, Ireland.

High-profile leaders' passion for sports does better than most PR campaigns to market their personal image, said Li Shengxin, a sports public relations expert and associate professor at Beijing Sport University.

"Showing their personal interest in sports, especially on big stages such as diplomatic activities, is a great way to demonstrate a vibrant and healthy image.

"Taking part in exercises like ordinary people is a great approach for leaders to earn public support. It's been proved by many election campaigns in the West," he said.

Before Xi and Li entered the sports spotlight, their predecessors did the same.