The NCP on Saturday demanded that trial in the Unnao case be fast-tracked after the victim, who was set ablaze on Thursday, died at a Delhi hospital.
NCP chief spokesperson Nawab Malik also asked if the accused were being shielded by the government machinery.
"We want the accused to be arrested at the earliest and punished through trial in a fast-track court," Mr Malik told reporters in Mumbai.
The 23-year-old Unnao rape victim, who was airlifted to Delhi and admitted to Safdarjung Hospital with 90 per cent burns, died on Friday night.
The woman was set ablaze by five men, including two of her alleged rapists, on Thursday morning when she was going to Rae Bareli to attend a court hearing.
The Uttar Pradesh government said on Saturday that the accused have all been arrested.
Mr Malik, meanwhile, also said demands of following the "Telangana pattern" in the Unnao case, from some quarters, are not right.
The four accused in the Hyderabad veterinarian's rape-murder case were killed in a police encounter on Friday.
"This is not right. In Hyderabad, people are saying, justice was delivered. But it was done in an unjust manner. Nobody has the right to punish someone," Mr Malik said, adding that proper judicial process be followed in the Unnao matter.
The NCP wants amendment to the law to ensure that trials of gang rape cases are completed within a stipulated period, and mercy petitions in such matters too should be decided within a fixed time, he said.
"Only then fear (of law) will be instilled," he added.