A former senior railway official who was charged with taking bribes of more than 24 million yuan ($3.9 million) pleaded guilty in court on Wednesday.

Su Shunhu, former deputy chief of the transport bureau under the then-ministry of railways — now China Railway Corp — stood trial at Beijing No 2 Intermediate People's Court. The sentence was not announced on Wednesday.

Su is the highest-level former railway official to stand trial since former minister of railways Liu Zhijun was convicted of corruption.

Liu, 60, received a suspended death sentence in July for accepting 64.6 million yuan in bribes and abuse of power.

Su's trial was scheduled to start at 10:30 am on Wednesday and was postponed to 1:45 pm because the car escorting him was caught in traffic in the morning.

In the courtroom, prosecutors accused Su of taking a huge amount in bribes from three companies from 2003 to 2011. In return, Su helped them resolve their railway transportation issues.

The largest sum Su took was 12.12 million yuan from Duan Li, a head of a Beijing company, after Su helped Duan solve commodity transportation problems.

Du sent the bribes in jewelry, gold bars and cash, the prosecutors said.

In court, Su admitted taking bribes and said he will not appeal to a higher court.

He wept while talking about his family's poverty during his childhood and his parents' poor health during the trial.

Su, born in 1954, worked for more than 20 years in the railway industry.

At the end of the trial, he said he felt sorry for his family and deeply regretted his behavior.

Zheng Fucheng, Su's lawyer from You Yin Law Firm in Beijing, said his client's attitude was positive and most of his bribes were returned.

Another former senior railway official will also stand trial soon.

Zhang Shuguang, former director of the bureau and the ministry's one-time deputy chief engineer, stands accused of accepting bribes of 47.55 million yuan, according to prosecutors in Beijing.

The successive corruption trials of former senior railway officials highlights the necessity of the anti-graft fight in the railway system, experts said.

Zhao Jian, a professor at Beijing Jiaotong University who specializes in railways, said the reform of the then-ministry of railways, which started in March, will help reduce corruption in the system.

In the past, the powerful transport bureau was engaged in many sectors, such as railway construction, the ministry's purchases and project bids. "Many companies and departments had to contact the bureau if they wanted to enter the market, which might breed graft,"Zhao said.

Now the power of the bureau has been decentralized, he added.

Ren Jianming, director of the Clean Governance Research and Education Center at Beihang University in Beijing, said the trials of the former railway officials can be taken as a warning to current railways staff.

But these cases also show that the anti-graft mechanism within the railway system is fragile, he said.

"After all, the reformed corporation is a State-owned enterprise. How to avoid new corruption is a problem, especially after a series of officials at SOEs have been put under investigation for corruption,"Ren said.

If the railway reform stalls, "I'm pessimistic about its future development and its anti-graft work,"he added.

Prosecutors investigated 141 crimes related to railway transportation staff from January to June, and the figure was 4.4 percent higher than that of the same period in 2012, according to the Supreme People's Procuratorate.