Alberta construction workers have uncovered two dead rats that likely hitched a ride into the province on a train.

Alberta, known for its rat patrol, has aggressively fought the rodent since the 1950s and boasts of being rat-free.

But police in the southern Alberta town of Taber announced Friday that the carcasses of two Norway Brown rats have turned up in a sewer on 52nd Street.

"That particular sewer line originates in the open storm ditch adjacent to the CPR rail line. It is likely the rats came off a train, entered the line and were quickly drowned when they hit the water," said Brandon Bullock, Taber's bylaw officer in a statement.

Authorities in Taber and Alberta Agricultre officials are "satisfied that they are not dealing with any breeding rats," the press release said.