India has demanded an apology from the US over the treatment of one of its diplomats who was arrested in New York last week on suspicion of visa fraud.
Government minister Kamal Nath urged the US to admit it had made a mistake.
US Secretary of State John Kerry's expression of "regret" over the incident was not enough, he said.
Deputy consul general Devyani Khobragade denies visa fraud and making false statements, after being accused of underpaying her Indian maid.
She was handcuffed and strip-searched last week - her arrest and alleged "humiliation" has led to a major diplomatic row between India and the US.
Ms Khobragade appeared in a Manhattan court last Friday and was freed on a $250,000 (£153,000) bail. She has in turn accused the maid, Sangeeta Richard, of theft and attempting to blackmail her.
Delhi has ordered a series of reprisals against the US. Security barricades around the US embassy in the city were removed and a visiting US delegation was snubbed by senior Indian politicians and officials.
On Wednesday, Mr Kerry spoke to Indian National Security Adviser Shivshankar Menon, who had described the treatment as "despicable and barbaric".
He said the "unfortunate" incident should not damage US-Indian relations.
But on Thursday, India said nothing short of an apology would suffice.
"They should admit that they have committed a mistake and only then will we be satisfied," Mr Nath said.
On Wednesday, angry MPs from several Indian parties called on the government to take tough action against the US and Prime Minister Manmohan Singh described Ms Khobragade's treatment as "deplorable".
But US prosecutor Preet Bharara said in a statement that Ms Khobragade "was accorded courtesies well beyond what other defendants, most of whom are American citizens, are accorded".
According to documents filed in a federal court in New York, Ms Khobragade wrote on a visa application that the maid would be paid $4,500 (£2,746) a month.
But investigators said she instead paid only $573 per month - less than the New York state minimum wage.
If found guilty, Ms Khobragade faces a maximum sentence of 10 years for visa fraud and five years for making false statements.
The US state department said that Ms Khobragade did not have full diplomatic immunity at the time of the alleged offences.
It said under the UN's Vienna Convention on Consular Relations, she is immune from arrest only for crimes committed in connection with her work.