Writes through with meeting results, background

SEOUL, Aug 19 (Reuters) - South Korean President Lee Jae Myung met on Tuesday with the heads of some of the country's biggest conglomerates, including Samsung and Hyundai Motor, who will accompany Lee for his summit next week with U.S. President Donald Trump, Lee's office said.

Lee and Trump will hold their first summit meeting in Washington on August 25 to discuss strengthening the countries' alliance and economic security partnership, including advancing a partnership in the manufacturing sector based on a tariff deal reached last month, Lee's office said previously.

Trump said last month the U.S. would charge a 15% tariff on South Korean imports as part of a deal to avoid even higher levies, while Seoul would invest $350 billion in the United States.

Uncertainties remain, however, since there was no written agreement, including over how the fund might work in practice and whether defence costs are brought in, given how Trump has long called for Seoul to pay more for U.S. troop presence.

The business leaders meeting Lee on Tuesday represented industries seen as key to negotiating manufacturing ties with the U.S., coming from sectors such as chips, shipbuilding, automobiles, defence, pharmaceuticals and energy.

The meeting was "to discuss ways to maximise economic performance at the South Korea-U.S. summit and listen to Korean companies' investment and purchase plans in the U.S.," presidential spokesperson Kang Yu-jung told a briefing.

Kang said shipbuilding cooperation with the U.S. was discussed during the meeting, but declined to elaborate.

Officials in Seoul have previously stated that a key component of the tariff deal is a partnership worth about $150 billion to help rebuild the ailing U.S. shipbuilding industry.

Samsung Electronics Chairman Jay Y. Lee, SK Group Chairman Chey Tae-won, LG Group Chairman Koo Kwang-mo and executives from businesses such as Hyundai Motor Group, Hanwha Group and others attended ahead of the trip to Washington, the Yonhap News Agency said.

Lee thanked the business leaders for their assistance in reaching the tariff deal with the U.S. and asked them to produce a lot of practical results when they accompany the president to meet Trump in Washington, Lee's office said.

(Reporting by Joyce LeeEditing by Ed Davies)

((joyce.lee@tr.com;))