The office of education secretary Ruth Kelly has been attacked by members of the protest group Fathers 4 Justice.
Fathers 4 Justice have claimed responsibility for the attack
Police are investigating after burglars broke into her Bolton West constituency office early on Thursday and glued locks shut and put slogans on the wall.
Fathers 4 Justice have claimed responsibility for the attack.
The group is believed to blame Ms Kelly for government policy that they say prevents parents from being able to see their children.
Elaine Risk, co-ordinator for the group in Greater Manchester, said: "I believe that she was locked out - the door was sealed and the letterbox was sealed and other posters were put up.
"We thought that maybe she would like to know how it feels to be denied access to her most beloved."
On Thursday night Greater Manchester Police confirmed officers are investigating the attack at Ms Kelly's office.