Uttam Khobragade, a retired IAS officer, also said he would join the protest being organised on Wednesday at Jantar Mantar in New Delhi to demand dropping of all charges against his daughter.
"Our government's stand was that since Devyani enjoyed diplomatic immunity, the arrest and prosecution could not have been launched at all. The UN has also confirmed that an advisor has diplomatic immunity from arrest. The fact that Devyani was an advisor has not been challenged by any one. The arrest was illegal and in light of all confirmation the charges need to be dropped," Khobragade told PTI.
Devyani, Deputy Consul General at the Indian mission in New York, was arrested in December and strip-searched over allegations of visa fraud relating to payments to her housemaid, triggering a diplomatic standoff between the two countries.
A New York grand jury had indicted her for visa fraud and making multiple false statements. The 39-year-old diplomat had left the US in January after she was granted immunity from charges of visa fraud and underpaying her maid.
"Some organisations are staging a dharna at Jantar Mantar in Delhi on Wednesday to demand charges against Devyani be dropped. I will also be joining the protest," Khobragade said.