New Delhi, Nov 6 (PTI): The Income Tax Department has picked 20,572 tax returns for "detailed scrutiny" suspecting discrepancies in incomes before and after demonetisation, official sources said today.

Separately, they said, the department has identified one lakh "high risk" cases of alleged tax evasion for detailed investigation.

According to the sources, 20,572 tax returns have been selected for detailed scrutiny after their profiles before and after demonetisation did not match.

A scrutiny procedure in the I-T department parlance denotes submission of a volume of records and testimonials, after which the taxman or the assessing officer makes sure that the return filed is correct and the filer has not evaded any tax.

The I-T department initiated the first phase of the 'Operation Clean Money' on January 31 this year to check black money and stash funds in the wake of the withdrawal of Rs 500 and Rs 1,000 notes, the two highest value banknotes of the time, from circulation on November 8 last year.

According to official data, 17.73 lakh suspicious cases involving Rs 3.68 lakh crore were identified by the taxman in 23.22 lakh bank accounts post demonetisation.

Responses from 11.8 lakh people for 16.92 lakh bank accounts have been received by the department through online medium till now.

The I-T department had conducted 900 searches between November 9, 2016 and March this year, leading to seizures of assets worth Rs 900 crore, including Rs 636 crore in cash.

The search led to the disclosure of Rs 7,961 crore undisclosed income, according to the official data.

During the same period, the department conducted 8,239 survey operations leading to detection of Rs 6,745 crore of black money, it said.