Tata Consultancy Services has taken action against six employees after finding them guilty of accepting favours from certain staffing firms in the appointment of contractual workers, Tata Sons chairman N Chandrasekaran said on Thursday.

The largest IT services exporter is investigating the role of three more of its employees, Chandrasekaran said while speaking at the TCS annual general meeting in Mumbai.

"We have banned six employees and also six companies," he said in response to questions from shareholders.

He said the company received two separate whistleblower complaints -- one pertaining to appointment of business associates or contractual workers in the US, and one in India, in late February and March, after which it investigated the allegations.

Chandrasekaran said he cannot quantify the favours these employees got but the banned employees behaved in such a way that they were favouring certain firms.

"The company will look at the whole BA (Business Associate) supplier management process and see what the weaknesses are and will completely tighten the process to ensure that we do not have such incidents," he said.

Earlier this month, some media reports suggested that TCS has suspended some employees for violating the company's code of conduct and some had pegged the gains made by the employees at Rs 100 crore.