Police in North Carolina are investigating the apparent firebombing of a Republican Party office - an incident that one official reportedly claimed was an act of “political terrorism.” Donald Trump blamed the attack on supporers of his rival Hillary Clinton.

With three weeks before election day, reports said the GOP’s Orange County headquarters in the town of Hillsborough, 40 miles from Raleigh, was attacked overnight on Saturday when a bottle of flammable liquid was thrown through the front window. Somebody also scrawled graffiti on an adjacent building that read: “Nazi Republicans get out of town or else.”

“The office itself is a total loss,” Dallas Woodhouse, executive director of the North Carolina Republican Party, told the Charlotte Observer. “The only thing important to us is that nobody was killed, and they very well could have been.”

“The flammable substance appears to have ignited inside the building, burned some furniture and damaged the building’s interior before going out,” local police said.

“The substance was housed in a bottle thrown through one of the building’s front windows.”

Hillsborough Mayor Tom Stevens said in a statement: “This highly disturbing act goes far beyond vandalising property; it willfully threatens our community’s safety via fire, and its hateful message undermines decency, respect and integrity in civic participation.”

He added: “I believe I speak for the overwhelming majority of people … Acts like this have no place in our community.”

North Carolina is one of the battleground states that will decide the outcome of the election. An average of polls collated by Real Clear Politics give a three point lead to Hillary Clinton over Mr Trump.