Singapore's former prime minister Lee Kuan Yew attends the Standard Chartered Forum in Singapore on March 20, 2013. Singapore's founding father Lee Kuan Yew, who will turn 90 next month, said in a new book published Tuesday that he feels weaker by the day and wants a quick death

Singapore's founding father Lee Kuan Yew has denied his policies were to blame for the city's low birth rate and said financial handouts for young couples would not solve the problem.

In excerpts from a new book to be launched later Tuesday, Lee insisted that the reluctance of couples to have more children was the result of changed lifestyles and mindsets, which no amount of financial perks could alter.

Despite a slew of so-called "baby bonuses" to encourage couples to have children, Singapore's total fertility rate last year stood at 1.20 children per woman, far below the 2.1 needed to maintain the native-born population.

The former prime minister, who retired from politics in 2011 and turns 90 next month, rejected as "absurd" suggestions that his "Stop At Two" children campaign in the 1970s played a part in the decline of current fertility rates.

Fearing that a population explosion would hit growth and overwhelm infrastructure, Lee's government instituted the tough measures to persuade young couples to have only two children.

The policy saw the government legalise abortion, encourage voluntary sterilisation and introduce disincentives for larger families wanting to live in public housing.

Large monetary incentives would only have a "marginal effect" in correcting the low fertility rate, he added.

"I cannot solve the problem, and I have given up," he wrote in his new book entitled "One Man's View of the World".

Excerpts from the book were published in the Straits Times newspaper on Tuesday ahead of the official launch.

"I have given the job to another generation of leaders. Hopefully, they or their successors will eventually find a way out," said Lee, who handed power to his deputy Goh Chok Tong in 1990 after 31 years in office. He stayed on as a cabinet adviser until 2011.

Lee's son, Lee Hsien Loong, is now prime minister of the affluent Southeast Asian island-state after succeeding Goh in 2004.

Singapore's birth rate has languished at low levels for decades, forcing the government to open the country to foreigners, who now comprise a third of the population.

The foreign influx, however, has also sparked protests from citizens and prompted the government to tighten immigration flows in recent years.

The declining fertility rate remains the biggest threat to Singapore's survival, Lee said.

He pointed to the example of Japan, which he said is on a "stroll into mediocrity" as the ranks of its elderly swell due to young couples not producing enough babies.

Japan's reluctance to open up to immigrants will further lead to its decline, he said.

"If I were a young Japanese and I could speak English, I would probably choose to emigrate," said Lee.