South Korea's military is 20 percent smaller than it was six years ago as the world's lowest birth rate shrinks the pool of men available for enlistment, according to a new report from the country's defense ministry.

South Korea's military has shrunk to about 450,000 people - a decline of 20% over the last six years, according to a defence ministry report released by a ruling party lawmaker on Sunday. Authorities say the main reason behind the decline is the country's dismal birth rate, which at 0.75 babies per woman is the world's lowest.

South Korea's military shrank by 20% in the past six years to 450,000 troops, largely due to a sharp drop in the population of males of enlistment age for mandatory service in the country with the world's lowest birthrate,