The Indian National Congress was served a show cause notice by the Income Tax (I-T) Department on Monday, after it failed to submit documents related to the alleged flow of black money from a Hyderabad firm to the party's coffers.

As well, senior Congress office bearers who were summoned by the I-T Department on November 4 did not show up.

During a recent raid, I-T sleuths found that a Hyderabad-based infrastructure firm had sent Rs 170 crore to the Congress through hawala channels.

These funds were siphoned out of government projects through bogus billings.

The Income Tax Department has found that the bogus billing was mostly done in projects allocated by the government to the company for economically weaker sections.