Inspector General of Police (IG) Om Prakash said the body of the girl was found in the Khajuwala area on Tuesday.
"Her family members have accused three persons, including two constables of Khajuwala police station, of raping the girl. Both the policemen have been suspended immediately and the matter is being investigated," he said.
The family members of the victim have refused to grant consent to conduct a post-mortem examination and demanded the immediate arrest of all the accused. They also staged a 'dharna'.
Superintendent of Police (SP) Tejaswani Gautam said efforts were being made to persuade the family members and relatives of the victim for postmortem.
Police said a case under various sections, including 376-D (gang rape), of the Indian Penal Code was registered with Khajuwala police station.
The family members have alleged that the policemen Manoj and Bhagirath along with the third accused took her to the house, where they gang raped and murdered her.
Citing call records, police said the victim and the key accused were known to each other.
Meanwhile, the role of the two constables is being probed.
The case is being investigated by additional SP Deepak Sharma.
The opposition, Bharatiya Janata Party (BJP) has cornered the Ashok Gehlot-led government over the incident.
Leader of the Opposition (LoP) Rajendra Rathore tweeted that the involvement of policemen in the incident of rape and murder of a girl in Khajuwala in Bikaner is a blot on the face of the government.
The suspension of the constables is merely a formality, due to which the family members of the girl are resentful towards the police administration, he added.
"It is unfortunate that till now both the accused constables have not been arrested. I demand the state government to take strict action against the guilty policemen in this case and arrest them," he said.
Food and civil supplies minister Pratap Singh Khachariyawas said in Jaipur that the matter was being investigated by the police and action against the guilty will be taken.