Australia and South Korea have formally signed off on a free trade agreement during a meeting in Seoul.

The Australia Korea Free Trade Agreement (KAFTA), which was secured late last year, will see tariffs on primary products that range from about 15 per cent to more than 500 per cent removed.

The foreign investment review threshold will also be lifted to more than $1 billion.

In his announcement of the formal agreement, Prime Minister Tony Abbott said the free trade agreement was able to be reached because of the trust between the two countries.

"Australia and South Korea are important and natural partners," he said.

"We are democracies, we are G20 countries ... we are countries that would much rather find friends than fights," he said.

"We are able to negotiate this agreement because Australia and South Korea trust each other."

Mr Abbott hailed the agreement as a "historic moment".

"Economically, there is huge untapped potential in the relationship between the two countries," he said.

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"The free trade agreement that we signed today is the first free trade agreement of your government, it is the first free trade agreement of my government and I believe it is one that we can both be very proud of."

"I am confident ... that over time, Australia can help to deliver food security, resource security and energy security to the people of Korea."

The deal with Korea is the second free trade agreement secured for Australia in two days, after Tony Abbott met with his Japanese counterpart, Shinzo Abe, in Tokyo yesterday.

That agreement will see advantages for beef and other agricultural products, with fruit and vegetables, seafood, cheese, sugar and wine among the winners.

However, earlier today, Government MP George Christensen hit out at the deal, questioning the value of an agreement that does not have a "significant benefit for Australian agriculture".