China's National Council of Social Security Fund said Thursday it will cooperate with a state investment company to "maintain and increase" the value of the fund.

The council said in a statement posted on its webiste that it signed a framework agreement for strategic cooperation on Wednesday with the State Development and Investment Corporation, China's largest state-owned investment holding company.

According to the agreement, the two sides will seek cooperation opportunities in fields of private equity fund, securities investment fund, trust investment as well as investment in projects.

They will also make contact at regular intervals to share investment information, and expand the cooperation scope on a mutually beneficial basis, the agreement said.

China's social security fund was established in August 2000 by the State Council. The fund aims to provide a solution to the aging problem and serve as a strategic reserve fund to support future social security expenditures.

The total value of the fund stood at 856.7 billion yuan (135.95 billion U.S. dollars) by the end of 2010, achieving an average annual yield of 9.8 percent since its establishment.