The number of college graduates outside the labor force has more than doubled over the past 15 years due to a rise in those who gave up looking for jobs amid a prolonged economic slump, government data showed Monday.

South Korean college graduates who are neither employed nor unemployed reached 3.35 million in 2015, compared with 1.59 million in 2000, according to the data by Statistic Korea.

From a year earlier, the number rose 4.7 percent.

"Companies recruit fewer workers due to lower global demand and deteriorating business environments. College graduates find it increasingly difficult to get the job they hoped for in terms of salary and welfare benefits," said Statistics Korea spokesman Sohn Young-tae.

"As a result, some of them have stopped seeking a job or gone to private educational institutes to be better qualified for the job they want."

Meanwhile, the number of jobless people with a college diploma has been on the rise since 2012. The jobless rate among them stood at 3.6 percent last year, the highest in 13 years since 2002 when the rate was at 3.7 percent.

"In short, one in five economically inactive people of 16 million was a college graduate last year," the spokesman said.  (Yonhap)