Bansal told the Rajya Sabha that there had been instances of the IRCTC website being inaccessible during morning hours and failure of some Internet ticket booking transactions even after deducting money.
"During the opening hours of booking, due to a sudden surge in online traffic, the IRCTC e-ticketing website transactions sometimes experience slowdown," he said.
In 2011-12, some 20-25 complaints were received every day against the Indian Railway Catering and Tourism Corp (IRCTC) "during peak (booking) period".
There had also been instances when money was deducted from credit cards multiple times while booking a single ticket, he said, responding to a question from BJP's Rajiv Pratap Rudy.
A sudden surge in online traffic during Tatkal booking also led the website to slow down, the minister said.