Diet deliberations on government-sponsored pension reform bills appear headed for turbulence, with the ruling and opposition parties locking horns over remarks by Prime Minister Junichiro Koizumi just days ahead of the Thursday start of debate on the contentious legislation.

"It's the start of a war," remarked a senior government official, predicting a stormy time for the government in pushing through the generally unpopular bills, which would cut pension benefits.

While the ruling and opposition camps had been at odds over the bills from the start, many ruling coalition lawmakers received a jolt Saturday when Koizumi suddenly expressed his support for integrating the three public pension schemes to correct the differences in the premium burden depending on occupation -- a key idea of the pension reforms advocated by the Democratic Party of Japan.