Devon and Cornwall Police say they have taken the unusual step of writing to local MPs about the new Terrorism bill.
The Government says the majority of the public support the Bill
It follows a claim by the Exeter MP and government minister Ben Bradshaw that the force does not want to see the Anti-Terrorism bill watered down.
Only the regions three Labour MPs voted for the measures, including detaining suspects for 90 days, as the bill passed its first reading by one vote.
The Force has refused to confirm what the letter says.
However they do say that it "reflects the view of the Police Service of England and Wales on a matter of national importance".
The police have been arguing since the July bombing that the current limit of 14 days is not enough time to conduct the necessary international investigations.
Mr Bradshaw claims that Devon and Cornwall Assistant Chief Constable Richard Stowe contacted all the region's MP's offering to brief them personally or arrange for them to speak to the head of Special Branch.
Liberal Democrat representative for Torbay Adrian Sanders was one of eight MPs from his party who, along with the region's five Conservative MPs voted against the bill.
He said: "It would be worth hearing what they (the police) have to say but they would have to make one heck of a case to break one of the fundamental principles of English law."
"I have no problem with the Metropolitan Police briefing the Home Secretary but I don't think it's the job of police to be lobbying individual members of Parliament."
The Government claims the vast majority of the public support the measures.