North Korean leader Kim Jong-un shakes hands with U.S. President Donald Trump during their historic U.S.-DPRK summit at the Capella Hotel on Sentosa island on June 12, 2018 in Singapore.

U.S. State Department officials recently met multiple times with North Korean counterparts in Hanoi and discussed planning a second summit between U.S. President Donald Trump and North Korean leader Kim Jong Un, a South Korean newspaper reported on Monday.

U.S. officials discussed the schedule for the second Trump-Kim summit while in contact with North Korean officials in the Vietnamese capital city, fuelling speculation that Vietnam could host the event, the Munhwa Ilbo reported, citing unnamed diplomatic sources in Seoul and Washington.

Vietnam has diplomatic relations with both the United States and North Korea, with North Korea maintaining a diplomatic office in Vietnam, and has the symbolic significance of a communist country that has reformed its economy, the newspaper reported.

A spokesperson for the U.S Embassy in Seoul did not immediately respond to requests for comment.

On Sunday, Trump told reporters in Washington that the United States and North Korea are "negotiating a location" for a second summit.

"It will be announced probably in the not too distant future," Trump said. "They do want to meet and we want to meet and we'll see what happens."

While the two sides had "a very good dialogue" and the American president had "indirectly" communicated with Kim, Trump said sanctions would be enforced until more progress is made.

In a nationally televised New Year address, Kim said he is willing to meet Trump again anytime to achieve their common goal of denuclearising the Korean Peninsula, but warned he may have to take an alternative path if U.S. sanctions and pressure against the country continued.

"I am always ready to sit together with the U.S. president anytime in the future, and will work hard to produce results welcomed by the international community without fail," Kim said.