Referring to Modi's speeches in Parliament yesterday, he told reporters that it was clear that the prime minister was not interested in answering "fundamental questions".
Defence Minister Nirmala Sitharaman, he said, had first announced that she would inform the nation about the cost of purchasing Rafale aircraft but was now saying she could not do so as it was a state secret.
"Which of her two statements are correct," he asked.
However, there was no reply, Gandhi said.
"There can be only one answer and it is that there is something fishy about this," he said.