Police are investigating a suspected arson attack on Derry Sinn Féin’s main constituency offices at Ráth Mór in Creggan.
A police spokesperson said a rear window was broken and a flammable liquid poured in shortly before midnight.
Sinn Féin MLA Raymond McCartney condemned the attack, saying: "This must be condemned as an attempt to attack the democratic process.
"It will not stop us working or the people of Derry. "It will be business as usual for Derry Sinn Féin, continuing to serve the people of the city an the wider north west.
Police said the scene was held overnight and enquiries are continuing this morning.