North Korea is carrying out a military assault exercise using a replica of South Korea's capital of Seoul, a lawmaker said Tuesday, citing government officials.

The exercise is focused on destroying key public facilities in the South Korean capital and is part of what North Korea threatened as "an operation to liberate Seoul," Rep. Lee Cheol-woo told reporters after his ruling Saenuri Party's meeting with officials from security-related state agencies.

On Saturday, Pyongyang threatened to advance into Seoul as South Korea and the United States conducted their biennial amphibious attack exercises on beaches near South Korea's eastern coastal city of Pohang.

The Saturday drill between the allies was part of the massive springtime simulated warfare exercises, Key Resolve and Foal Eagle, which the countries kicked off last week.

In protest of the drills, North Korea could carry out military provocations along the inter-Korean border or send drones to South Korea, the lawmaker said.

North Korean leader Kim Jong Un (Yonhap)Terrorist attacks in the capital or rear areas, missile launches or GPS jamming could possibly be ventured, Lee noted.

"The (South Korean) military is having preparatory training against the possibilities," he said.

The ruling party called the meeting of officials from the defense and foreign ministries, the spy agency and the police earlier in the day as military tensions are on the rise between the two Koreas.

Earlier this year North Korea conducted its fourth nuclear test and long-range missile launch, resulting in the adoption of a new round of United Nations Security Council resolutions that prohibit the export of jet fuel to the communist country.

Seoul is currently checking North Korea's key transit points overseas, including in Beijing, Shanghai, Moscow and Thailand, in order to find any flow of aviation fuel into the North, he said.

Concerning North Korea's warning earlier in the day that it will conduct another nuclear warhead detonation test and fire off ballistic missiles, Lee said the government is trying to verify if Pyongyang is moving forward with its threat. (Yonhap)