SINGAPORE, May 15 (Reuters) - Singapore will inaugurate Lawrence Wong on Wednesday as its new prime minister and fourth leader since independence six decades ago, completing a carefully calibrated power transfer designed to guarantee continuity in the wealthy city-state.

Wong, 51, comes from among a crop of so-called "4G" leaders, a new generation of politicians hand-picked by the long-ruling People's Action Party (PAP) to take over the reins of the key Asian trade and financial centre.

Wong will retain his current position as finance minister and takes charge of a country led for two decades by Lee Hsien Loong, the 72-year-old son of Lee Kuan Yew, the founder of modern Singapore who stayed in politics until his death in 2015.

The succession has been long coming, with Lee's plans of stepping down before he turned 70 upended by the pandemic, and by a transition fumble when his anointed successor unexpectedly ruled himself out of the running in 2021.

Wong's inauguration will take place on Wednesday evening.

When the date for the handover was announced last month, Wong said he accepted the responsibility "with humility and a deep sense of duty" towards Singapore and its 5.9 million people.

"Every ounce of my energy shall be devoted to the service of our country and our people," Wong pledged in a video on his social media accounts.