BELEK, Turkey -- Japanese Prime Minister Shinzo Abe has told the G20 summit of global leaders that he sees an overall improvement in relations with China, a spokesman said on Sunday, although sticking points remain around the East China and South China Seas.

China, the world's second-largest economy, and Japan, the third-largest, have a difficult political history, with relations stained by the legacy of Japan's World War Two aggression and conflicting claims over a group of East China Sea islets.

"The prime minister said that Japan-China relations as a whole see gradual improvement," Yasuhisa Kawamura told reporters at a briefing on the sidelines of the Group of 20 (G20) summit in Turkey, which Abe is attending.

However, Kawamura added that issues around the East China Sea and South China Sea remained a "concern" for the region.

Abe has in the past been critical of China's assertiveness in the South China Sea, through which much of Japan and South Korea's trade and energy supplies pass.

Abe told South Korea's president this month that he wanted cooperation between the two countries and the United States in maintaining an open and peaceful South China Sea.

In a sign of the improvement in Sino-Japanese relations, Abe has met Chinese President Xi Jinping twice since last November.

Kawamura also quoted Abe as saying that Japan will take anti-terrorism measures at home and to protect its citizens overseas in the wake of the attacks in Paris that killed more than 120 people.

The Paris attacks, which have been claimed by Islamic State, cast a shadow over this year's G20 summit in the Turkish coastal province of Antalya, a meeting that was supposed to focus on boosting global growth.