The US and Japan have finalised negotiations on a new trade agreement that will enable Washington to increase its agricultural exports to the Asian country, US President Donald Trump and Japanese Prime Minister Shinzo Abe announced.

The agreement will allow US producers to increase their agricultural and livestock exports, along with other products, totalling "billions of dollars", Trump said on Sunday in remarks to reporters with Abe, Efe news reported.

Both leaders said that certain details still remain to be ironed out in the final text, which could be signed next month during the UN General Assembly meeting in New York.

The accord focuses on three areas -- agriculture, industrial products and digital commerce.

Given that the latest Chinese reprisals in the bilateral trade war launched by Trump have negatively affected a good portion of US agricultural exports to the Asian giant, Trump focused on emphasizing the advantages for the farming sector in the pact reached with Japan.

Specifically, he said that Japan will buy "hundreds of millions of dollars" worth of US corn after China failed to fulfill its commitment to buy that product from US farmers, although he emphasized that other markets valued at up to $7 billion per year in other US exports would also be opening up as a result of the pact.

"It's very good news for our farmers and ranchers," US Trade Representative Robert Lighthizer said, adding that the US would be able to sell not only more corn to Japan, but also more beef, pork, wheat, dairy products, wine and ethanol.

The new trade deal with Japan, long a staunch US ally, will give Trump at least one key achievement at the G7 summit, although he has been at odds with other allies during the meeting hosted by French President Emmanuel Macron.

Specifically, he said that Japan is the main buyer of US beef valued at $2 billion per year and that this agreement will enable to US to compete in that country with exports from countries in the European Union and in the Pacific.

Lighthizer added that the agreement will enable Japan to avoid having the US increase tariffs on Japanese automobiles.

Abe said that the pact had been finalized after "intense negotiations," adding that it will have "an immense economic impact" on both countries.