Liberal Democratic Party lawmakers made an ambitious proposal Thursday to raise the ratio of immigrants in Japan to about 10 percent over the next 50 years.

The frankness of the suggestion reflects the seriousness of Japan's population decline, which is marked by a rapid increase in the elderly population and a falling birthrate that threatens to undermine future economic growth.

"There is no effective cure to save Japan from a population crisis," the proposal said. "In order for Japan to survive, it must open its doors as an international state to the world and shift toward establishing an 'immigrant nation' by accepting immigrants and revitalizing Japan."