"We did," Trump told journalists when asked if a deal had been reached, without giving further details.

"We reached a deal. We did a lot of different things. Great session," the US leader said.

But the US President then appeared to walk back the claim, telling a dinner with APEC leaders including Lee that the deal was "pretty much finalised".

"We pretty much finalised our trade deal and we discussed some other things to do with national security, etc. And I think we came to a conclusion on a lot of very important items," Trump said.

In July, Trump said Washington had agreed to cut tariffs on South Korean imports to 15 percent in exchange for a $350-billion investment pledge.

Steep auto tariffs remain in place, and the two governments were divided over the structure of the investment pledge.