TOKYO - Japan plans to oppose a United Nation's proposal pushed by the United States for arms embargo against South Sudan, local media quoted government sources as saying on Wednesday.

The Japanese government is concerned that if the arms embargo resolution is adopted by the UN Security Council, South Sudan will take revenge against UN representatives on the ground, particularly peacekeepers, including Ground Self-Defense Force (GSDF) members from Japan, Kyodo News quoted a diplomat as saying.

U.S. Ambassador to the United Nations Samantha Power on Monday criticized Japan's reluctance to the draft resolution.

"The arms embargo is a tool not only for protecting the people of South Sudan," she said. "It is also a tool for protecting peacekeepers."

According to the UN resolution drafted by the United States, for one year after the resolution's adoption, all member states are to immediately take "necessary measures" to prevent the direct or indirect supply, sale or transfer of arms or related material into South Sudan.

Since 2012, Japan's Ground Self-Defense Force unit has been deployed to build infrastructure in South Sudan as part of the UN mission.

Last month, Tokyo assigned its troops controversial new security task in peacekeeping operations in South Sudan, allowing Japanese troops to fight overseas for the first time in seven decades, including rescuing UN staff and others under attack, in accordance with Japan's controversial new security legislation that came into force in March.

However, critics fear the changes could erode the pacifist Constitution and embroil Japanese troops in overseas military actions for the first time since the end of World War II.

The new duties, however, have been controversial among people in Japan who believe Self-Defense Force members, in light of the Constitution, should stay away from missions that essentially assume the use of weapons.