SEOUL (Reuters) -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 reciprocal tariffs.

U.S. Secretary of State Marco Rubio said the new deadline as set out by Trump in a letter addressed to South Korean President Lee Jae Myung meant there was still time for the countries to work out an agreement, Lee's office said later.

Trump said on Monday he would impose the tariff on goods from South Korea starting on August 1, posting the letter to President Lee on his social media platform along with one to Japan's leader.

South Korea's Industry Ministry said in a statement that the letter effectively extended a grace period on the implementation of reciprocal tariffs by the United States.

"We will step up negotiations during the remaining period to reach a mutually beneficial result to quickly resolve the uncertainties from tariffs," it said.

"We also plan to use it as an opportunity to improve domestic systems and regulations to resolve the trade deficit that is a major interest of the United States and advance key industries through a manufacturing renaissance partnership between the two countries," it said.

South Korea earned a record surplus of $55.6 billion from trade with the U.S. in 2024, up 25% from 2023, led by rising car exports, according to Korea Customs Service data.

Trump said in the letter to Lee that "our relationship has been, unfortunately, far from reciprocal," inviting South Korea to present a proposal to open "your heretofore closed trading markets" and eliminate tariff and non-tariff barriers.

South Korea's effective tariff rates stand at near-zero under a free trade agreement first signed in 2007 then revised in 2018 under Trump's first term, according to economists.

South Korea's top trade envoy and the country's presidential security adviser have travelled to the United States in recent days for trade and defence talks as Asia's fourth-largest economy raced to seek an exemption from Trump's threatened tariffs.

National Security Advisor Wi Sung-lac met Rubio in Washington on Monday to discuss the countries' alliance and ongoing trade negotiations and agreed that a summit meeting between Lee and Trump would help advance cooperation, Lee's office said.

"Tariff letters to major trading partners including South Korea were sent out today but there is still time until tariffs are implemented on August 1 so he hopes the two countries can communicate closely to reach an agreement before that," Lee's office cited Rubio as saying.

Trump also appeared to indicate that he was open to negotiation.

Asked if the deadline was firm, Trump said: "I would say firm, but not 100% firm. If they call up and they say we'd like to do something a different way, we're going to be open to that."

South Korea was slow to negotiate for an exemption from Trump's tariffs, first agreeing to work out a package deal but holding "technical discussions" before moving to high-level negotiations after Lee took office in June 4.

Lee won a snap election after his predecessor's December martial law declaration, which he said had greatly impaired the country's response to U.S. trade policy and new tariffs.

The Industry Ministry in the statement conceded it did not have enough time after the start of a new administration in South Korea to reach an agreement with the United States on all issues despite intense negotiations.