Japan's foreign minister called on North Korea to improve relations with the South before any other talks on nuclear and foreign aid issues could begin, dpa reported.
Seiji Maehara arrived in Seoul to meet with South Korean Foreign Minister Kim Sung Hwan and other officials on bilateral and international concerns, particularly security regarding Pyongyang.
The one-day visit came after Maehara had expressed willingness to hold direct talks with North Korea this year to discuss Pyongyang's nuclear and missile programmes and past abductions of Japanese nationals. North Korea welcomed the overture.
That move raised some concern that the wrong message was being sent to the provocative regime that shelled a South Korean border island in November and has made ominous threats of nuclear war.
Maehara said Saturday that South Korea, the United States and Japan have taken a united stand, demanding the secretive communist state demonstrate a commitment to eliminate its nuclear weapons' programme and improve relations with Seoul.
He said Japan would continue to back South Korea's position in the conflict, calling the attacks "unpardonable."
"It is North Korea that engaged in provocative acts, we cannot agree to talks for talks' sake and (Pyongyang) is required to take specific action," Maehara was quoted as saying by the Yonhap news agency. "That is the position of South Korea, the US and Japan."
Relations between Seoul and Tokyo have been warm since Japanese Prime Minister Naoto Kan offered an apology in August for the 1910-45 colonial rule over the peninsula. He also promised to return ancient royal Korean books taken during that period.
Japan is seeking greater security and economic cooperation with South Korea. Its defence minister visited Seoul this week, and efforts are moving toward free-trade negotiations.