Thailand's fugitive former prime minister Thaksin Shinawatra is to deliver two speeches in Tokyo Tuesday, kicking off a week-long Japanese visit that has sparked a fierce political dispute in Bangkok.

Leaders of the ruling Pheu Thai party said they would ask Thailand's election committee on Tuesday to dissolve the opposition Democrat Party over what they claim are false accusations against Foreign Minister Surapong Tovichakchaikul.

Democrat Party leaders asked the election commission last week to remove Surapong from his post, charging he had illegally asked Japan to give Mr. Thaksin a visa. On Monday, Surapong filed a defamation complaint against the Democrat leaders, saying they had no evidence for their claims.

Pheu Thai, headed by Mr. Thaksin's younger sister Yingluck Shinawatra, won an overwhelming election victory last month, driving the Democrats from power. Pheu Thai is closely allied with Mr. Thaksin, who was overthrown in a 2006 military coup and who claims his subsequent conviction on corruption charges was politically motivated.

Thaksin is living in self-imposed exile in Dubai to avoid a two-year jail term. The Democrats say the new government is obliged by law to do everything it can to bring him to justice.