WASHINGTON (REUTERS) - The United States notified South Korea on Wednesday (July 12) it plans to start negotiating amendments to a five-year-old free trade agreement with Seoul and called a meeting to kick off the talks for next month (August).

The announcement came months after US President Donald Trump said he would either renegotiate or terminate what he called a "horrible" trade deal.

US Trade Representative Robert Lighthizer, acting on Mr Trump's instructions, said the joint committee under the US-Korea Trade Agreement (KORUS) would meet in Washington next month.

No date has been set.

"Since KORUS went into effect, our trade deficit in goods with Korea has doubled from US$13.2 billion (S$18.1 billion) to US$27.6 billion, while US goods exports have actually gone down," Mr Lighthizer said in a statement.

"This is quite different from what the previous Administration sold to the American people when it urged approval of this Agreement. We can and must do better," he said.

Mr Trump, in an interview with Reuters in April, blamed the trade deal on his 2016 Democratic presidential election opponent, Mrs Hillary Clinton, who as secretary of state promoted the final version of the agreement before its approval by Congress in 2011.

"It's a horrible deal, and we are going to renegotiate that deal or terminate it," Mr Trump said in the interview.

A South Korean trade official told Reuters on Thursday (July 13) that it will hold the proposed joint committee either in Seoul or Washington, but this does not necessarily mean that South Korea will renegotiate the deal.

"We will meet and discuss mutual interests and concerns. Our stance is that we have not agreed on renegotiation of the deal," Mr Yeo Han Koo of South Korea's Trade Ministry said over the phone.

He said South Korea believes the deal is mutually beneficial, and the two countries need to first establish whether the US trade deficit with South Korea is caused by the trade deal or is a result of other fundamental economic issues.

On July 1, Mr Trump met South Korean President Moon Jae In and said the US was renegotiating what he characterised as a "rough" trade deal with South Korea agreed to five years ago by his predecessor, Mr Barack Obama.

KORUS was initially negotiated by the Republican administration of President George W. Bush in 2007, but that version was scrapped and renegotiated by President Barack Obama's Democratic administration three years later.