Already mired in its worst economic slump in decades, Japan could see its growth decline even further as its citizens age and its population shrinks, the government said in an annual economic assessment released Friday.

The report suggests Japan needs to take stronger measures to encourage people to have more children, and to make its domestic markets more attractive to foreign investment.

"Japan is experiencing aging unprecedented in history," said Jun Saito, director of economic policy and analysis at the Cabinet Office, which authored the report.