The United States and North Korea have been in continued contact to resume working-level talks on dismantling the regime's nuclear weapons program, with Washington still waiting for Pyongyang's response on the time and venue, South Korea's ambassador to the US said Wednesday.

The US and North Korea had been expected to hold working-level negotiations by mid-July in line with an agreement between US President Donald Trump and North Korean leader Kim Jong-un during their impromptu meeting at the inter-Korean border on June 30.

With no announcement yet on the date or location, Pyongyang has warned that the talks' resumption would be affected by whether Seoul and Washington go ahead with their joint military exercises scheduled for next month.

"I understand that the North and the US are continuing communication for the resumption of working-level talks," South Korean Ambassador to the US Cho Yoon-je told reporters during a briefing. "The US side is still waiting for a response from the North regarding the specific time and location."

Asked Monday if the talks have been scheduled, Trump said no, adding that there was "very positive" correspondence recently with the North.

"When they're ready, we'll be meeting," he told reporters at the White House.

The ambassador said he expects the talks to resume as soon as the North is ready, given that communication between the sides has been "smooth" and that it was agreed to by the leaders.

On the increasingly bitter trade dispute between South Korea and Japan, Cho said the Embassy, along with visiting officials from Seoul, has delivered South Korea's concerns about its potentially damaging effects on trilateral security cooperation and US businesses to the US government, Congress and think tanks.

The ambassador was referring to the flare-up in Seoul-Tokyo tensions caused by Japan's July 4 curbs on exports of key semiconductor and display panel materials to South Korea.

"It appears that the US is contemplating what role it can play (in the dispute)," he said. "(The US) seems to be of the stance that it wants South Korea and Japan to find a diplomatic solution, and if in the process it can be of help, it will play a facilitating role."

Meanwhile, the South Korean government is reviewing "various measures" after the US asked partner nations last week to join a US initiative to form a military coalition aimed at safeguarding freedom of navigation in the Strait of Hormuz off Iran, Cho said.

The ambassador also cast Trump's visit to Seoul last month as a "great success," citing what he said was a demonstration of President Moon Jae-in and Trump's close relations and trust, and a reaffirmation of the allies' joint position that a firm alliance serves as the foundation for regional peace, stability and prosperity. (Yonhap)