* S.Korea aims to implement the deal on Jan. 1, needs parliamentary approval
* S.Korea wants exemptions from potential U.S. tariffs (Add comment from South Korean government, background)
WASHINGTON/SEOUL, Sept 18 (Reuters) - President Donald Trump said on Tuesday a U.S. trade deal with South Korea has been fully renegotiated and may be signed at the United Nations, where leaders have gathered for the 73rd session of the General Assembly.
In March, the two countries agreed in principle to revise the deal, which Trump had criticised for increasing U.S. trade deficits with South Korea.
"The trade deal with South Korea has been fully renegotiated and is ready for signature," Trump told a news conference.
"We may sign it at the United Nations or shortly thereafter. It was a terrible deal for the United States, now it's a fair deal."
South Korea's trade ministry is preparing for the possible signing between President Moon Jae-in and Trump during the U.N meeting next week, a ministry official said.
She said it was hoped the deal could be implemented from Jan. 1, 2019, but the schedule depended on a parliamentary approval.
Separately, the Trump administration is considering whether to impose tariffs of up to 25 percent on U.S. imports of autos and auto parts from south Korea and other countries under the "Section 233" investigation.
South Korea has said it should be exempt from the tariffs, saying it had already made concessions in autos under the revised trade deal.
Euisun Chung, executive vice chairman at Hyundai Motor Group, on Sunday left for the United States to meet U.S. Commerce Secretary Wilbur Ross and other officials to discuss tariff exemptions, a presidential aide said. (Reporting by Jeff Mason in WASHINGTON and Hyunjoo Jin in SEOUL; Writing by David Alexander; Editing by Eric Beech)