Prime Minister Lee Hsien Loong met China's top graft-buster Wang Qishan yesterday, and thanked him for his contributions to Sino-Singapore ties over the years.

"We are very honoured to be here just before the 19th Party Congress," Mr Lee said in his opening remarks, referring to a twice-a- decade meeting next month when the Chinese Communist Party (CCP) reshuffles its top leadership. The congress will start on Oct 18.

"We know it is a very busy time for you and for all your colleagues, and we are very appreciative that you are spending time to cultivate this bilateral relationship and take our cooperation another step forward."

Mr Wang, 69, heads the CCP's Central Commission for Discipline Inspection, or anti-corruption watchdog, and sits on its top decision-making body, the Politburo Standing Committee (PSC).

He said that since China embarked on a path of reform and opening up more than 30 years ago, its leadership has been following what Singapore does very closely.

Singapore, he noted, is one of the countries he has had the most contact with. When he was vice-premier, Mr Wang co-chaired the Joint Council for Bilateral Cooperation (JCBC) from 2008 to 2012 with his Singapore counterpart.

The JCBC, the top body steering bilateral ties between the two countries, is currently co-chaired by Singapore Deputy Prime Minister Teo Chee Hean and Chinese Vice-Premier Zhang Gaoli, who is also a PSC member.

In their meeting, Mr Lee thanked Mr Wang for his contributions to bilateral ties in his various capacities over the years, the Prime Minister's Office said. They also exchanged views on the experiences of Singapore and China in tackling corruption and learning from each other's best practices, it added.

Yesterday's meeting was notable as Mr Wang has kept out of the limelight and has seldom met foreign guests since becoming a key enforcer of President Xi Jinping's anti-corruption campaign in 2012.

Even as Mr Wang said he was "pleasantly surprised" by Mr Lee's request to meet him, it is in keeping with the top leaders' desire to build on bilateral ties forged by earlier leaders.

On tackling corruption, Chinese officials have visited Singapore's Corrupt Practices Investigation Bureau, including Politburo member Sun Chunlan in 2013. A crucial reform proposal launched in November that year made direct references to Singapore's model for preventing and fighting corruption.

In his remarks, Mr Wang also paid tribute to the late Mr Lee Kuan Yew, saying that he "had the privilege of having personal conversations with him on multiple occasions".

"He (was) such a visionary figure full of political wisdom," he said. "I gained a lot every time I talked with him... I am really greatly saddened by his passing. He was indeed a great man."