SEOUL, March 7 -- China, South Korea and Japan advanced their free trade deal negotiations further at the fourth round of talks held in Seoul for four days through Friday, the South Korean trade ministry said.

Trade delegates from the three Asian countries gathered in Seoul for talks on the trilateral free trade agreement (FTA), which ran from Tuesday to Friday, the Ministry of Trade, Industry and Energy said in a statement.

The delegates discussed modality, or basic guideline, on the goods sector and the range of future negotiations.

In the goods sector, the three parties talked about main points of the modality, including way of liberalization and negotiation process.

Working group meetings were held to discuss the main points of written agreement about rule of origin, customs, trade remedy, sanitary and phytosanitary (SPS) and technical barriers to trade ( TBT).

For service, investment, competition and general rules, separate working group meetings were held to discuss the main points of written agreement.

Talks among experts were held to negotiate on whether to include government procurement, e-commerce, food and environment sectors in the trilateral free trade pact.

The fifth round of talks will be held around July in China, with detailed schedules to be discussed later, the ministry said.

Meanwhile, the ministry said the South Korean government will seek to maintain consistency in negotiations for the China-South Korea FTA, China-S.Korea-Japan FTA and Regional Comprehensive Economic Partnership (RCEP).

Since President Park Guen-hye took office in February last year, South Korea sought actively to participate in the RCEP negotiations. The RCEP is a multilateral FTA that will include China, South Korea, Japan and 10 members of the Association of Southeast Asian Nations (ASEAN) as well as India, Australia and New Zealand.

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

In 2012, combined gross domestic product of the three Asian nations reached 14.3 trillion U.S. dollars, accounting for around 20 percent of the world total and 70 percent of Asia's total. The combined export and import volume were 5.4 trillion dollars, or 35 percent of the world total, in 2012.