Alberta Agriculture has set up a toll-free number to report rats in an effort to keep the destructive rodents out of the province.

The toll-free number, 310-RATS (7287), lets people report sightings of the pest.

The province prided itself for being rat-free for decades, but faced unusual infestations in southeastern Alberta in 2012 and last year.

Norway rats are considered to be extremely destructive with the potential to ruin crops and spread disease.

Rat inspector Bruce Hamblin says municipalities are responsible for eradicating the varmints, but people sometimes don't know where to call to report a sighting.

"We talked to people who couldn't find an easy number to call," he said.

"Sometimes calls were going to fish and wildlife officers and some of the other agencies before finally being directed to Alberta Agriculture.

"The new 310-RATS phone line is just a more efficient tool to help ensure Alberta remains rat-free."

Alberta focuses its rat-control efforts within a 29-kilometre-wide zone along the Saskatchewan boundary from the central Lloydminster area south to the U.S. border.

Municipalities along this corridor get special grants from the province to monitor the pests.

The province is so serious about preventing the rodents from getting established in Alberta that it is illegal to have any types of pet rats.

Phil Merrill, Alberta Agriculture's provincial rat specialist, says there were 16 confirmed reports last year, including pet rats.

The yearly average is up to 10 single rat sightings and up to three infestations, generally in the rat-control zone.

When rats are found they are killed. The province considers the larger infestations in 2012 and 2014 at the Medicine Hat dump, which is just outside the rat-control zone, to be unusual.

During the campaign last year to root out the pests at the dump, an 80-metre-long nest was found that took a team of workers and two excavators six hours to destroy.

Alberta Agriculture says Norway rats live near people or their structures. They can't survive in natural areas or survive winter in farm fields.

The rodents are not native to North America but were introduced along the east coast in 1775 and spread slowly westward.