SEOUL -- China, South Korea and Japan discussed modality, or basis guideline, on the trilateral free trade agreement (FTA) at the third round of talks, Seoul's trade ministry said Friday.

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, which was held in Tokyo for four days through Friday, according to the Ministry of Trade, Industry and Energy (MOTIE).

Working group meetings were held to discuss a wide range of topics such as indication of origin, customs, trade remedy, sanitary and phytosanitary (SPS) and technical barriers to trade (TBT) along with services, investment, competition, general rules and intellectual property rights.

Talks among experts were made about e-commerce, environment, government procurement and food sectors.

The fourth round of negotiations was scheduled to be held in Seoul in February 2014, with detailed schedules to be discussed further later, the ministry said.

The three Asian countries have seen increasingly close economic and trade relations and have become important partners and markets to each other.

In 2012, combined gross domestic product of the three nations reached $14.3 trillion, accounting for some 20 percent of the world total and 70 percent of Asia's total. The combined import and export volume of the three countries were $5.4 trillion, or 35 percent of the world total.