Detectives from the Serious Crime Branch are examining allegations of misuse of expenses by Stormont Assembly members.
The PSNI said officers were assessing the claims of “potential criminality”.
The series of allegations against a number of Assembly members were outlined in two recent documentaries by BBC Northern Ireland Spotlight, the second aired on Tuesday night.
The programmes shone particular focus on how representatives of the Assembly’s two largest parties – the Democratic Unionists and Sinn Fein – claimed money over the last decade.
Sinn Fein MLAs have claimed nearly £700,000 in expenses for research apparently conducted by a company run by the party’s finance managers. Sinn Fein insisted that research had been done for constituency and Assembly purposes.
The reports also raised questions about the use of public money at a number of DUP and Sinn Fein constituency offices.
Both parties have defended their actions and criticised the BBC coverage.
The SDLP and Ulster Unionists have also moved to counter claims made against some of their representatives.
A spokesman for the PSNI said all the allegations were now being assessed by officers.
“Detectives from Serious Crime Branch are currently scoping allegations of potential criminality made in recent media reports,” he said.
Alliance Party leader David Ford called for police to step in.
“The Assembly needs to bring in external forensic auditors for all current and previous expenses claims and allow the police to investigate the allegations made in the Spotlight programme. We are talking about potential fraud in the region of tens of thousands of pounds.”
Mr Ford, who is also Stormont’s justice minister, added: “It is vital that there is openness and transparency in politics and that the public can be confident that expenses are being used appropriately.”
TUV leader Jim Allister agreed that it was “imperative that the PSNI is called in to investigate” and said he had written to the Chief Constable.
In particular, he pointed to the supply of £700,000 of public money by Sinn Fein to a research company.
SDLP MLA for Foyle Colum Eastwood called for the immediate reform of the Assembly expenses and Office Cost Expenditure system following revelations in the Spotlight documentary.
“What we need now is an urgent root and branch reform of a system that has clearly lost the confidence of the public and the confidence of many public representatives who were open and transparent about claims at all times,” he said.
Conservative Party spokesman Mark Brotherston said: “The expenses system at Stormont must be changed to prevent MLAs using personal claims to fill the coffers of political parties.” He added: “Once again a BBC documentary has asked searching questions about Stormont expenses and once again the parties have reacted with hostility rather than contrition.”