The day after he publicly walked out before a Lower House vote on the controversial extra budget, Kenta Matsunami was dismissed from his post as parliamentary secretary for the Cabinet Office, Chief Cabinet Secretary Takeo Kawamura said.

The Cabinet tapped Yoshiro Okamoto, a House of Representatives member of the Liberal Democratic Party, to succeed Matsunami, also a Lower House LDP member.

Asked for the reasoning behind the decision, Prime Minister Taro Aso told reporters: "It is extremely simple. He left the session while he was in the post of a parliamentary secretary. A parliamentary secretary is a member of the Cabinet and needs to follow the decisions the government has made."

Aso also said Matsunami's move came out of the blue. "I did not anticipate it," he said.

Kawamura said at a press conference, "Mr. Matsunami deserves dismissal as he, despite being a member of the Cabinet, abstained from voting for the second extra budget (for fiscal 2008) — one of the government's most important plans — at the Lower House plenary session (Tuesday), opposing the government's policy."

On Tuesday, Matsunami walked out of the Diet session, telling reporters that a ¥2 trillion portion of the budget allotted for a cash handout program should be used for medical services and employment instead.

Matsunami later tendered his resignation as secretary to Kawamura, who accepted it.

But Aso opted to sack Matsunami in an apparent bid to prevent more members of the LDP-New Komeito ruling bloc from defecting when the Lower House votes again on bills related to the second budget.

"In his resignation, Mr. Matsunami denied any intention of making any countermoves against the government or (ruling bloc)," Kawamura said, indicating the LDP is unlikely to expel him.