UPDATED 4.15pm: Cabinet Minister Anne Tolley's delivering a message to those who attacked her Whakatane electorate office overnight.

Someone smashed the glass, bent the bars and pushed three firebombs through the window.

Ms Tolley has visited her office this morning and said anti-TPP graffiti was done on a mural near her office.

"We're presuming that's all part of the same group, and it's anti-TPPA."

Tolley's message to those responsible is, it achieves nothing.

"If you've got a problem, if you've got concerns, I'm always available to talk to. And I have been talking with people about TPPA. People who have some legitimate concerns, and the only way to deal with that is to talk about them."

Tolley said local anti-TPP protestors have contacted her today to say they don't agree with the attack on her office.

Security will be ramped up in the next week or so.

The minister said she's concerned for her staff more than her self.

1XX reporter Georgia May said there have been some tensions in recent days over the signing of the TPPA.

MORE: Police satisfied with handling of TPP protests

"There's also graffiti on the wall there as well, with a terrible spelling of John Key's name - spelled 'Jhon'."

There was a small march in the town yesterday which was peaceful - but earlier this week there was an attempt to set fire to flags in the middle of a roundabout.  

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Georgia May said there is minor smoke damage, along with graffiti.

"Luckily there was not a lot of damage done, all I could see on the ground was a green bottle and that has obviously been thrown through the glass window into Anne Tolley's office, and there's a smashed hole in the door."

Michael Woodhouse's electorate office was also targeted by TPP protesters yesterday, though there was no damage caused in this instance.