North Korea's leader Kim Jong Un has reaffirmed his policy to increase nuclear weapons production.

The state-run Korean Central Television reported on Tuesday that Kim delivered a speech about national governance on the 76th anniversary of the country's founding on Monday.

Addressing senior members of the ruling Workers' Party, Kim justified the strengthening of military power.

In his speech, he claimed that the United States-led military bloc is evolving into a nuclear-based system, posing "a grave threat" to his country. He was apparently referring to the security cooperation among Japan, the US and South Korea.

Kim went on to say that North Korea is "now perfectly carrying out the policy" of "increasing the number of nuclear weapons by geometrical progression."

The North Korean leader added that his country is "a responsible nuclear weapons state."

In a speech reported in January last year, Kim also stressed the need to "exponentially" increase the number of the country's nuclear warheads.

Washington has laid out a policy to continuously strengthen its extended deterrence, which includes its nuclear forces, to defend Japan and South Korea. This has prompted North Korea to again assert its intention to enhance nuclear deterrence.