One is believed to be top Tory councillor Geoff Driver, who is due to be installed as leader of Lancashire County Council on Thursday.
The other three are understood to be former County Hall chief executive Phil Halsall, David McElhinney – who was chief executive of the now defunct One Connect and its sister organisation Liverpool Connect – and Ged Fitzgerald the current Liverpool City Council chief executive and former Lancashire County Council chief executive.
The four are currently being questioned at Skelmersdale Police Station.
A police spokesman said they had been arrested “on suspicion of conspiracy to pervert the course of justice and witness intimidation.”
More details to follow.