Singapore's former chief justice Yong Pung How, who died yesterday morning at the age of 93, was "one of Singapore's finest sons", said Prime Minister Lee Hsien Loong.

In a Facebook post, PM Lee said Mr Yong, also a former banker who had helped set up sovereign wealth fund GIC (formerly known as the Government of Singapore Investment Corporation) and served at the Monetary Authority of Singapore (MAS), had left an indelible mark on the country's legal profession and society.

But it was in the judiciary that Mr Yong left his deepest legacy, PM Lee noted in a condolence letter to Mr Yong's wife.

A close friend of Singapore's late founding prime minister Lee Kuan Yew, Mr Yong agreed when Mr Lee asked him to return to the law in 1989, and to become chief justice in 1990, said PM Lee.

"Mr Lee wanted him to shake up and modernise the courts, which had become slow and out of date," said PM Lee.

To enhance efficiency, Mr Yong set up specialist courts, increased the size of the bench and introduced major reforms to court processes to shorten the time taken to dispose of matters, he said.

To encourage judges and magistrates to start hearings on time, he would even occasionally appear at the Subordinate Courts at 8.30am to personally greet latecomers, PM Lee said. This contributed to High Court case disposal times dropping from five years to below 18 months in less than a decade.

"Our legal profession, and indeed our society as a whole, owes him an immense debt of gratitude for this accomplishment," said PM Lee.

Mr Yong regularly visited university campuses to identify the ablest law students and encourage them to apply to become justices' law clerks, said PM Lee, and some have since become judges of the Supreme Court and senior officers in the legal service.

"In these last few weeks, as he lay ill in hospital, his former law clerks were among his most regular visitors," said PM Lee.

"Most importantly, Mr Yong understood how Singapore worked, the fundamental realities of our society, and how laws should be administered and applied in our context so as to ensure good governance for Singaporeans."

PM Lee added that Mr Yong and Mr Lee Kuan Yew, who studied law at Cambridge University together, had a friendship based on mutual respect. "(It was) forged in their fight against colonialism, and reinforced by their shared commitment to build this nation. Even in old age, they enjoyed each other's companionship and would often have meals together," he said.

Tributes from across the government flowed yesterday after news of Mr Yong's death.

President Halimah Yacob said she was deeply saddened by Mr Yong's passing.

"Mr Yong was a shining ex-ample of a gentleman who responded to the nation's call to serve," she wrote in a condolence letter to his wife.

During his time as managing director of MAS and GIC, Mr Yong used his extensive experience in commercial banking to successfully reorganise the management of Singapore's financial reserves, said Madam Halimah.

He also continued to serve Singapore in various capacities after retiring as chief justice, such as being part of the Council of Presidential Advisers from 2007 to 2013, she said.

"He had left behind a better place for our future generations," she added.

Deputy Prime Minister Heng Swee Keat said Singaporeans have Mr Yong to thank for a fairer and more efficient judicial system.

"Those of us who served in the Singapore Police Force during the 1980s knew that the system then often took a long time for justice to be served. Mr Yong shared the belief that justice delayed is justice denied - he introduced wide-ranging reforms to improve the efficiency of the court process," said DPM Heng.

Chief Justice Sundaresh Menon recounted how the courts "groaned under a backlog of 2,000 suits which, at that time, would have taken many years to dispose of" when Mr Yong took office as chief justice.

But Mr Yong, "a prodigiously talented individual", met the challenge with steely resolve, CJ Menon said. He introduced the system of pre-trial conferences, established the Night Courts, launched the Electronic Filing System and Technology Courts, and opened the Singapore Mediation Centre.

"By the opening of the legal year in 1994, the backlog had largely been reduced to a footnote in our legal history. In successfully modernising the justice system and expeditiously clearing the backlog, Mr Yong's tenure as chief justice perhaps stands as the most consequential in our history," he said.

His jurisprudential approach was also marked by pragmatism, boldness and conviction, said CJ Menon.

"In civil law, Mr Yong's approach was practical and commercially sensitive, undoubtedly informed by his long experience in business and finance... In criminal law, Mr Yong saw the first responsibility of the courts as the protection of the public, tempered by a sensitivity to the individual's potential for rehabilitation.

"While his emphasis on deterrence as a principle of criminal justice is well known, Mr Yong never overlooked those who deserved a second chance," said CJ Menon.

In a Facebook post, Home Affairs and Law Minister K. Shanmugam said Mr Yong was a "selfless titan who dedicated himself to building up Singapore and her institutions".

He was privileged to have been a practising lawyer when Mr Yong was a High Court judge and then chief justice, said Mr Shanmugam, recalling that Mr Yong was "sharp, immensely practical, and formidable to appear before".

He also "shook the Bar out of its lethargy and modernised it", said Mr Shanmugam, noting that Mr Yong had introduced close to 1,000 initiatives in the then Subordinate Courts within a decade of taking office.

These efforts contributed greatly to Singapore now being regarded as a trusted international legal centre with a strong judiciary, he added.

Minister for Social and Family Development Desmond Lee said Mr Yong was his first "big boss" when he started working in the legal service in 2001. "He held exacting standards, but would patiently listen to his staff and to his clerks, even if they (had) contrarian viewpoints... He was genuinely interested in people and was prepared to give advice when we sought it.

" 'With affection and respect' was how he would often sign off on photos he sent to staff each year. For me, and I would dare say for all of us who have ever worked under him, we held Chief in the highest regard, and with deep respect and affection too."