Freedom of speech has its limits at Self-Defense Forces-related facilities, Chief Cabinet Secretary Yoshito Sengoku said Thursday, drawing further protests from opposition lawmakers concerned the Defense Ministry is increasingly engaging in censorship.

"Even if one is a civilian, (remarks) made inside the SDF facilities are to be restricted, because if that is not the case, there could be a misconception that SDF members were involved," Sengoku told the Upper House Budget Committee.

The controversy started when the Defense Ministry issued a notice last week advising defense officials and top military brass not to invite guests who could make remarks of a political nature that could compromise the SDF's neutrality, to SDF events.