There's been an arson attack on the constituency office of Fine Gael TD Michelle Mulherin.
Gardai were called to the building in Ballina at around 7pm after a report of a broken window, but discovered a fire when they arrived.
The fire has been extinguished.
There was nobody in the office at the time.
Gardai have launched an investigation.
Deputy Mulherin has been under scrutiny after it emerged she had made calls from Leinster House to a private phone in Kenya.
The bill for the calls, which were made between 2011 and 2013, amounted to over €2,000.
Ms Mulherin says she made the calls but they were not personal in nature.