Police from three separate forces will examine allegations surrounding Labour funding as Gordon Brown comes under mounting pressure over donor scandals.
Scotland Yard is already investigating how the identity of property developer David Abrahams, who gave more than £600,000, was kept secret from regulators.
Detectives in Scotland are examining complaints about a donation to the party's Scottish leader Wendy Alexander from a Jersey-based businessman.
And Durham police will talk to Liberal Democrat MP Chris Huhne about his concerns over the decision to grant Labour's "disguised" donor permission to build a business park.
The row over Mr Abrahams' donations intensified over the weekend when the businessman claimed as many as 10 senior Labour officials were aware of his funding arrangements.
Peter Watt resigned as the party's general secretary after admitting he was aware of the practice - but the Prime Minister says he only found out when it was exposed by a newspaper.
But Tory leader David Cameron said it "beggars belief" that the Prime Minister had been kept in the dark and accused Mr Brown of trying to "spin his way out of a scandal".
Mr Abrahams also claimed the chief fundraiser appointed by Mr Brown, Jon Mendelsohn, had not only known since April that he was using proxy donors but said it sounded "a good idea".
Mr Mendelsohn dismissed the allegation as "fictional and completely untrue".
As the Westminster row raged on, attention also turned north of the border after a formal complaint was lodged with Strathclyde Police by a Scottish National Party researcher.
