South Korean Foreign Minister Cho Hyun said his country and the United States had reached a rough agreement on security in tandem with ongoing tariff negotiations, Yonhap news agency reported.

In an interview published on Thursday, Cho also said the U.S. was reviewing a currency swap deal, which was a key demand from South Korea in tariff talks, but signalled it was not optimistic.

Washington had agreed to lower tariffs on imports from South Korea in return for a $350 billion investment package, but follow-up negotiations to hammer out details, including the structure of the investment package, have stalled.

Cho said the two sides were "actively" negotiating but South Korea might need more time to strike any trade deal with the U.S. than Japan, which signed on to the details of its investment package last month.

Meanwhile, Seoul and its ally Washington have also been looking at a deal in security areas such as an increase in South Korean defence spending, which is part of the broader package aimed to push down U.S. tariffs.

The minister said Seoul was seeking to announce the security agreement with the U.S. before the summit of the Asia-Pacific Economic Cooperation group in Gyeongju, South Korea in late October.

U.S. President Donald Trump is expected to attend the APEC meeting.

Trump has said South Korea should be paying for its own military protection and suggested it needed to pay more for the U.S. troop presence there.

South Korean President Lee Jae Myung said on Wednesday the country would boost next year's defence budget by 8.2%, highlighting the importance of stronger self-defence.

"In the security field, an agreement has already been reached in general, which allows us to increase our national defence capabilities in necessary areas," Cho told Yonhap.

Working towards the security deal, top South Korean officials have said the two countries are making progress on giving more rights to South Korea on nuclear fuel processing for industrial purposes.

That is currently not allowed under an existing agreement between the two countries.

Cho said he did not rule out a possibility of Trump meeting with North Korean leader Kim Jong Un, as some "speculative" media reports suggested.

The South Korean president suggested the U.S. president try to meet with Kim during his trip to South Korea.

Last month, Kim said he was open to talks with the U.S. if Washington stopped insisting his country give up nuclear weapons, North Korean state media reported.