(Adds comments from prime minister, politician)
TOKYO, June 22 (Reuters) - Japan's Transport Ministry has forecast the first ever fall in road use, something that could affect Prime Minister Junichiro Koizumi's plans to privatise road-building corporations, the Yomiuri Shimbun said on Saturday.
The drop-off in traffic is forecast to start in 2030 and contrasts with estimates of a 50 percent rise in traffic by 2020, on which current highway construction and loan-repayment plans are based, the paper said.
Road use would peak in 2030 at a total of 897 billion car km (557 billion car miles), due mainly to lower than expected business use, the Yomiuri said. The new forecasts are based on population, which is expected to peak in 2006, as well as projected economic activity, the paper said.
The appearance of the road use report, which is updated every five years, will necessitate a re-think of current construction and loan repayment plans, and affect Koizumi's plans for the road-building corporations, the Yomiuri said.
Koizumi on Friday named members of a panel charged with making recommendations on the privatisation of road-building groups such as the Japan Highway Public Corp, which have been criticised for wasting money on unnecessary roads in rural areas.
In an attempt to restore faith in the reform programme that helped him sweep to power just over a year ago, the prime minister tapped Naoki Inose, a journalist and vocal advocate of change. Inose has in the past called for a freeze on the construction of motorways.
"Now you know my resolve to implement reforms remains unchanged," Koizumi told journalists after announcing the panel members' names on Friday.
But the move infuriated LDP politicians known as the "doro zoku" or "road tribe," who are based in constituencies that rely on road-building to provide jobs.
"All I want to say about his choice of panel members is that it was again influenced by his desire to be popular," Kyodo news agency reported the powerful former LDP Secretary General Makoto Koga as saying in a speech in Nagoya on Saturday.
"I'm concerned that the appointed members include someone who can be called a destroyer, rather than a reformist," Kyodo reported him as adding.
The panel is due to hold its first meeting on Monday, local media reported.