Former internal affairs minister Kunio Hatoyama, whose older brother, Yukio, is the prime minister, served notice Monday that he was exiting the Liberal Democratic Party, saying he was ready to form a new force.

The prime minister, the president of the ruling Democratic Party of Japan, meanwhile said it is unlikely he will cooperate with his sibling.

"I don't intend to work with him," the prime minister told reporters. "I will not refer to other parties' situations."