South Korea said it planned to intensify trade talks with the United States and considered U.S. President Donald Trump's plan for a 25% tariff from August 1 as effectively extending a grace period on implementing the duties.

Trump warned Japan and South Korea against retaliation by increasing their own import taxes, saying that the US would further increase the tariffs over and above the already imposed 25 percent.

South Korean President Lee Jae Myung says his administration is doing its best to reach a tariff deal with the US, as Seoul's top negotiator heads to Washington again this weekend. Mr Lee held his first media conference to mark 30 days in office on Jul 3.