Are you seeing these backlinks as referrer hits in your stats? If so then it may be referrer log spam. These are fake hits that seem to be from pages that have links to your site, but when you check the page, there is no link. The site owner sends a fake hit so it shows up in your logs and they hope you will later visit their site when you see it.
If you get a lot of them you can report it to the hosting provider for the site that is showing up in your logs. Most hosts will close the account of someone that is spamming like that...!