South Korea's presidential office Cheong Wa Dae hailed the new U.N. Security Council resolution on North Korea on Sunday, noting the resolution, which imposes fresh sanctions against the communist state, has also been supported by China and Russia, Pyongyang's two closest allies.

"In the past, it took an average three months for China to express its support for a UNSC resolution," a ranking Cheong Wa Dae official told reporters, while speaking on condition of anonymity.

"This time, it took only about a month for China to agree to a new sanctions resolution," the official said.

The remarks came hours after the highest decision-making group of the world body unanimously passed the new sanctions resolution against the North, which may cut the impoverished nation's annual exports by up to one-third or some $1 billion.

The US-drafted resolution came after the North test-fired what it claims to have been an intercontinental ballistic missile on July 4. Pyongyang test launched another ICBM on July 28.

"Starting July 28, the UNSC resolution was passed only in about a week," the Cheong Wa Dae official noted.

US President Donald Trump earlier called the resolution the "single largest economic sanctions package ever on North Korea."

Still, the latest UNSC resolution against the North, the eighth of its kind, was widely considered only partially effective as UNSC members failed to reach an agreement on a US-proposed ban on oil exports to the North, reportedly due to Chinese opposition.

The Cheong Wa Dae official insisted the resolution was more meaningful in that it was endorsed by all UNSC members, including China and Russia.

"Most of all, we believe it is much more important to stress the fact that it was passed by a unanimous vote instead of the oil export ban omission," the official said.

"And that is why I wish to note China and Russia too are taking this issue very seriously."