Of the four arrested, three are from the Bahujan Samaj party, which largely represents the Dalits or the former "untouchable" castes, while the fourth belongs to the Hindu nationalist Bharatiya Janata party (BJP).
Katara, who was also a member of the BJP, was sacked from the party after the story broke.
Last Thursday, a Delhi court ordered Katara to spend 10 days in police custody after officers said they needed to take him to a number of places in the Punjab to ascertain the extent of his alleged involvement in the trafficking.
Police have said they suspect he may have smuggled people to Britain and North America in the past.
Many Indian MPs are seen as corrupt and Social Watch India, a watchdog, said in a report last year that more than 30 per cent of politicians aged between 36 and 45 years were facing criminal charges.