Bot Comments

HELP!

I dont know what happened, but every day hundreds of comments are made in a post on my blog.
They are made by a “bot”, I believe.
They are advertisements, strangers, as an example:

Agiwuxodobylodiw:

Japan with 24 on the Oricon charts. This is simply the best ringtone video ever. Paris’ hardscrabble 19th district. – deal tmobile ringtones without subscriptions main
Drew Barrymore, and Tony Randall. – day free ringtones for motorola phones fact
i730 ringtones with lyrics – Why not go after the music industry instead? Leonard’s mother is a psychiatrist. The film opens with a girl crying for help. Many houses have tripled in value, at least.
Shown in the United Kingdom. Mobile Operators worldwide. Until this time, only two lines had been used. Both are aimed at first-time cell phone users. Over the summer, Andy plans his and Angela’s wedding. – current downloadable ring tones left

How I clean it or block it??