SINGAPORE - President Halimah Yacob has conveyed her condolences to the Philipines on the death of former president Benigno Aquino III, saying he had made invaluable contributions to the friendship between the two countries.

In a letter to her Philippine counterpart Rodrigo Duterte on Friday (June 25), Madam Halimah said Mr Aquino "strengthened the economic foundation of the Philippines during his term in office. He worked tirelessly for Filipinos and left a legacy of enduring prosperity for the country".

Mr Aquino also made "invaluable contributions to deepening the friendship between the Philippines and Singapore", she said. "I will always cherish the memory of meeting him during his state visit to Singapore in 2011."

"Our thoughts are with his family and the people of the Philippines during this time of loss," said Madam Halimah.

Mr Aquino died peacefully in his sleep at 6.30am on Thursday due to kidney failure and diabetes, according to his family. He was 61.

The son of revered democracy icon and former president Corazon Aquino, Mr Aquino served as president from 2010 to 2016.

Prime Minister Lee Hsien Loong and former president Tony Tan have also written to Mr Aquino's family to offer their condolences, said the Ministry of Foreign Affairs in a statement on Friday.

PM Lee also posted on his Facebook page on Friday: "I had the pleasure of meeting President Aquino many times over the years, including when he visited Singapore in 2014. We worked together to strengthen the ties between our two countries, and to advance regional cooperation in Asean and Apec."

"He felt a strong obligation to serve, especially due to his family history - both his parents were prominent political icons in the country. As president, he brought stability and rapid economic progress to the Philippines, and pursued policies that improved the lives and well-being of his fellow countrymen," said PM Lee.

"My heart goes out to his family, and to the Filipino people. His passing is a great loss to the Philippines."