Singapore has begun seven days of national mourning for Lee Kuan Yee, the country's founding father who was as respected as he was feared.

Lee, 91, succumbed to pneumonia on Monday morning at Singapore General Hospital, where he was admitted in February, the government announced.

It said Lee had "passed away peacefully" and in a live broadcast a reporter for state television called the death the "awful and dreaded" news.

State television broke away from its regular programming with a tribute to Lee's life and achievements. 

World leaders - including President Barack Obama, Chinese President Xi Jinping and Narendra Modi, India's prime minister - paid tributes to the man credited with turning the city-state into a mordern nation with some of the highest per capital income.

A self-proclaimed authoritarian who saw the world in stark realist terms, Lee commanded respect from Singaporeans, who this year will celebrate the country's 50th anniversary of independence.

Showing the physical frailty that comes with his 91 years, Lee made relatively few public appearances in recent years.

But by many accounts, Singapore's first and longest-serving prime minister remained mentally active, continuing to write occasional books and opinion columns, and sometimes stepping into policy debates about the island-nation's future.

With the 50th independence anniversary only months away, Singaporeans wonder aloud what their country will look like without its founding father.

"Mr Lee's biggest legacy to Singapore is to have Singapore continue robustly as a unique state even after his passing," Eugene Tan, an associate professor of law at Singapore Management University, told Al Jazeera.

"A Singapore that cannot endure and thrive beyond Mr Lee would be an indictment of Mr Lee's leadership and legacy."

Japanese occupation  

Born Harry Lee Kuan Yew on September 16, 1923, a British subject in colonial Singapore, Lee omitted his English name Harry after reading law at Cambridge University.

He saw his country survive a three-year Japanese occupation during World War II, and a short-lived merger with Malaysia that brought an end to British colonial rule.

He became Singapore's first prime minister in 1959 when it became a self-governing state within the Commonwealth, and continued in the post from the country's independence in 1965 until he stepped down in 1990.

Lee went on to assume successive ministerial positions.

"The Father of Singapore" as he came to be known, first took power amid a host of problems including a multi-racial and multi-religious society with a history of violent outbursts, inadequate housing, unemployment, a lack of natural resources such as a water supply, and a limited ability to defend itself from potentially hostile neighbours.

Whip-smart, self-assured and unflappable, Lee earned plenty of criticism along the way.

"If someone living in Singapore in the 1950s could have entered a time machine and travelled to the Singapore of today, he would have found the transformations of this island literally unbelievable," SR Nathan, a former Singapore president, said at a September 2013 conference on the legacy of LKY, as he is commonly referred to.

Central to Lee's vision were the creation of good governance, political stability, a quality infrastructure, and improved living conditions.

"Had we not differentiated Singapore in this way, it would have languished and perished as a shrinking trading centre and never become the thriving business, banking, shipping and civil aviation hub it is today," Lee said in 2007.

Source: Al Jazeera and agencies