China, South Korea and Japan started the fourth round of negotiations on a trilateral free trade agreement (FTA) in Seoul on March 4.

The fresh round of negotiations, lasting from March 4 to 7, focused on modalities of tariff reduction, ways of opening service trade between the three countries and investment as well as certain areas and fields of the agreement, according to the Chinese delegation.

South Korea's Trade Minister Yoon Sang-jick said although these talks may not always go smoothly, the negotiations are "moving toward an end."

South Korean farmers previously opposed such an agreement, fearing that a free trade pact would flood the market with cheap produce.

The three Asian countries talked about the trilateral FTA's modality such as how to make a draft of liberalization for goods at the third round of negotiation held in Tokyo in 2013.

China, South Korea and Japan have seen increasingly close economic and trade relations and have become important partners and markets to each other.

The FTA is expected to create one of the world's largest markets, as combined gross domestic product of the three countries will account for 20 percent of world total and the combined imports and exports volume will account for 17.5 percent of global trade.