The Singapore government hopes to deepen its relations with Malaysia during the reign of the 15th Yang di-Pertuan Agong Sultan Muhammad V.
"I am confident that Malaysia will enjoy good progress during Your Majesty's reign," said Prime Minister Lee Hsien Loong in his congratulatory letter which was made available to the media late Thursday.
Lee noted that Malaysia and Singapore shared a long history built on close people-to-people ties.
"Looking forward, joint projects like the Kuala Lumpur-Singapore High-Speed Rail will bring the peoples of Malaysia and Singapore even closer together.
"I hope to deepen the relationship between our countries during Your Majesty's reign," said Lee.
Sultan Muhammad V took the oath of office as the 15th Yang di-Pertuan Agong at Istana Negara last Tuesday.
"On behalf of the Government of Singapore, I would like to extend my warmest congratulations on the occasion of Your Majesty's assumption of office as the Fifteenth Yang di-Pertuan Agong of Malaysia," Lee wrote.
Lee also extended his appreciation to Sultan Muhammad V for attending the lying-in-state of the republic's first Prime Minister.
"We deeply appreciated Your Majesty's attendance at the lying-in-state of the late Mr Lee Kuan Yew in March 2015," Lee said.
"My wife joins me in wishing Your Majesty every success," he added.
Meanwhile, Singapore President Tony Tan Keng Yam said he is confident that Malaysia under Sultan Muhammad V's guidance will continue to develop and prosper.
"The relations between Malaysia and Singapore are deep and multi-faceted, and the two countries share many common interests. I look forward to working with Your Majesty to strengthen these relations," he said in his congratulatory letter.
"On behalf of the people of Singapore, I extend my warmest congratulations on the historic occasion of Your Majesty's assumption of office as the Fifteenth Yang di-Pertuan Agong of Malaysia," he wrote.
"My wife and I offer our best wishes for Your Majesty's good health, happiness, and success," he added.