The first tranche of the bonds, worth 20 billion-30 billion yuan, is expected to be issued soon, with maturity set at seven and 20 years, one of the sources said, adding that Guotai Junan Securities Co and China International Capital Corp would act as underwriters.

Another source confirmed the 100 billion yuan size of the bond and said the first tranche of about 30 billion yuan would be issued later in September.

The Ministry of Railways, a major borrower in China's bond market, was not immediately available for comment.

The ministry has come under pressure from investors casting doubt over its credibility and operational ability since China's deadly train crash last month.

Two high-speed trains in eastern China crashed on July 23, killing 40 people and triggering a wave of criticism toward the railway ministry as well as concerns over the reliability of the country's railway systems.

Copyright Reuters, 2011