A widening probe into corruption in China's powerful Railways Ministry is raising questions over the scale and pace of its multibillion-dollar drive to build costly high-speed railways, though it is unlikely to derail the program.

Along with concerns over financing and other issues, at least one proposal for scaling down the showcase program is due to be presented to a top advisory group meeting in Beijing this week during the annual session of China's National People's Congress, a state media report said Wednesday.

Critics of the high-speed railways expansion say ticket costs are too high and the services do not really meet the needs of average travelers in many areas.

"Railway development plans should be more down to earth and take into account what people really need," Wu Youying told the Shanghai Daily. Wu is a member of the advisory group, the Chinese People's Political Consultative Congress.

While Wu's proposal will likely gain little traction given the resources invested in high-speed rail, the corruption investigation is a blow to the program, which until recently has rivaled China's space efforts in terms of national pride and importance.

The scandal surfaced last month with the dismissal of Railways Minister Liu Zhijun amid allegations of so-far unspecified "severe violations of discipline." Reports in the financial news magazine Caixin Media and other local media say the allegations involve kickbacks, bribes, illegal contracts and sexual liaisons.

Dismissals of top Communist Party officials are rare, since they can damage the party's credibility among a public already jaded by widespread graft. But the current leadership has sought to burnish its image with various cleanup campaigns.

Allegations against Liu have been circulating for several years, but with the leadership nervous over a possible spillover of the unrest in the Middle East, amid online calls for protests in China, the party may have felt now was a good time to act.

"If you punish him, the results can only be positive. This is very well calculated on their part," said Ding Xueliang, a China expert at Hong Kong's University of Science and Technology.

In the latest development, Zhang Shuguang, an engineer in charge of research and development of the country's high-speed railways, was removed, also for alleged but unnamed disciplinary violations, the official Xinhua News Agency announced late Tuesday.

Zhang oversaw innovation of China's high-speed rail technology, according to an earlier Xinhua report that quoted him describing his triumphs in negotiations with foreign companies.

"Our strong point is that Chinese producers are united to form a 'China corps,'" Zhang said.

The same epic account cited Liu, the ousted railways minister, as likening the country's high-speed railways to "dragons in the sky."

The concerns over the railway program are not limited to corruption.

The country's 56,000 miles (91,000 kilometers) of passenger railways are the world's longest and, in some cases, the fastest, but are still working beyond their capacity.

China will spend 700 billion yuan ($106 billion) in railways construction this year, railway officials say, as it works toward its goal of having 8,000 miles (13,000 kilometers) of high-speed rail in place by the year's end.

The costs are raising worries over financing. Major state-owned railway and railcar building companies with shares listed in Hong Kong and Shanghai increasingly are relying on bonds and bank loans to finance projects, with onerous repayment obligations that may be difficult to meet given the revenue projections for many projects.

Annual interest payments on loans for a high-speed rail link between Beijing and the nearby city of Tianjin, for example, will exceed the line's annual revenues. Other lines face similar woes, the financial magazine Caijing reported, citing Zhao Jian, a professor at Beijing's Jiaotong University.

"It seems that political impetus, rather than market needs, lies behind China's railway frenzy," said a recent commentary in the Chinese newspaper Global Times, describing the boom as "incredibly risky."

The speed of construction has some experts asking about safety issues, but the top gripe among critics of the program is that the emphasis on bullet trains is coming at the expense of slower but more practical services.

Despite the increasingly public criticisms over the high-speed rail program, it is unclear what impact the scandal will have on future and current projects. They include a 870-mile (1,400-kilometer) high-speed link between Beijing and Shanghai, the country's commercial capital, that is due to open in June.

China, meanwhile, is going head-to-head with global rivals like Siemens, Japan Railways and Bombadier and winning overseas contracts, among them a recent $13 billion deal to build eight railway lines in Iran and plans for joint construction of a high-speed railway in Kazakhstan.