Seven of 14 Chinese activists arrested after landing on disputed islands left Japan by plane Friday and the others were being deported as well, relieving some tension from one of the territorial rows Tokyo has with its neighbors.

The protesters had traveled by boat from Hong Kong to the uninhabited East China Sea islands controlled by Japan but also claimed by China and Taiwan. They were arrested Wednesday after five of them landed without authorization on one of the five-island group, known as Senkaku in Japanese and Diaoyu in Chinese.

Chief Cabinet Secretary Osamu Fujimura said earlier Friday that Japan would not press further charges against the activists.

"The decision is strictly based on domestic laws, not swayed by emotions," Fujimura said, denying any political consideration.

He said some of the activists had thrown concrete blocks onto coast guard patrol boats but did not cause any injury or major damage that would subject them to criminal charges.

Prime Minister Yoshihiko Noda called the incident "extremely regrettable." Other ministers said they will study how they can block future landing attempts, including possibly increasing the penalty for illegally landing on the island.

"Illegal entry and landing with the specific purpose of violating our country's territorial sovereignty should carry heavier punishment than usual," National Public Safety Commission chief Jin Matsubara said.

The arrests have prompted protests in Hong Kong and Beijing, and Japan's move to quickly deport the activists was seen as an attempt to avoid further inflaming protests.

Seven of the 14 activists left on a commercial flight from Japan's southern island of Okinawa, and the others were being flown to a nearby island to take their boat home later Friday from there, Justice Ministry officials said.

China had demanded immediate release of the activists, saying their capture by Tokyo was hurting bilateral relations. Dozens of people protested in Beijing, Hong Kong and several other major cities, praising the activists as heroes and burning Japanese flags.

Japan says it has controlled the five main islands for more than 100 years. It has been trying to place four that are privately held under state ownership to bolster its territorial claim.

The deportations will relieve some tension between Tokyo and Beijing, but that may not last. A group of ultra-conservative parliamentarians and local politicians are going by boat to the waters off Senkaku over the weekend to mourn for the victims of a boat accident near Senkaku at the end of World War II.

Japan, meanwhile, moved to act tougher on another island dispute, this one with South Korea.

It threatened to cancel upcoming ministerial talks to protest remarks and actions by South Korean President Lee Myung-bak that stirred animosity and said it wants to take the island dispute to the International Court of Justice.

Lee recently visited the islands, which are controlled by South Korea but also claimed by Japan, angering Tokyo. Lee also said this week that Japanese Emperor Akihito should apologize to Koreans if he wants to visit South Korea and condemned Japan over its wartime sexual slavery of Korean women.

Fujimura, the chief Cabinet secretary, said Japan "within days" would seek South Korea's consent to take the case to the international court to rule on the overlapping claims on the islands, called Takeshima in Japanese and Dokdo in Korean.

South Korea quickly dismissed the proposal, with the country's Foreign Ministry spokesman Cho Tai-young calling it "not even worth a passing note."

"Our government will sternly deal with any Japanese provocations over Dokdo," Cho said in a statement.

Japanese Finance Minister Jun Azumi called Lee's remarks and actions "unacceptable" and suggested the possibility of postponing talks with his South Korean counterpart scheduled for later this month.

Japan also could consider terminating a bilateral foreign exchange scheme to help support the South Korean won, Azumi said.