Official campaigning began Tuesday for three House of Representatives by-elections seen as a litmus test for Prime Minister Junichiro Koizumi's Liberal Democratic Party ahead of an upcoming general election.

Nine people filed applications to run in the Lower House by-elections, to be held April 27, with three vying in the Tokyo No. 6, four in the Ibaraki No. 7, and two in the Yamanashi No. 3 constituencies.

The elections in the three constituencies will be held the same day as a House of Councilors by-election in the Ibaraki Prefecture constituency and the second and final stage of the quadrennial unified local elections nationwide. Official campaigning for the Upper House by-election is already under way.