EDMONTON - Alberta has joined a growing list of provinces calling on online classified service Craigslist to remove sex ads in Canada.

In a letter to Craigslist CEO Jim Buckmaster, Justice Minister Alison Redford and Solicitor General Frank Oberle say the ads "appear to be a thinly-veiled cover for human trafficking."

The letter further states that allowing the ads to continue likely helps support a "despicable" crime.

Saskatchewan, Manitoba and Ontario have already asked the San Francisco-based service to pull the ads in order to help curb sexual trafficking of minors.

Craigslist has said it's willing to meet with officials in Ontario.

Several US states have previously persuaded Craigslist to drop the ads.