Greenville Fire Chief Ruben Brown Sr. told a news conference on Wednesday afternoon that investigators had determined the fire at Hopewell Missionary Baptist Church was "intentionally set."

"Samples and evidence have been collected from inside the church and are being analysed to determine the accelerant or ignition source," Brown said.

Earlier in the day he said no one was injured in the Tuesday evening blaze, but the church was extensively damaged.

"We're investigating this as a hate crime," Greenville Police Chief Delando Wilson told a news conference early on Wednesday. "We feel that the quote on the church is intimidating.

"It tries to push your beliefs on someone else, and this is a predominantly black church and no one has a right to try to influence the way someone votes in this election."

Wilson told the Wall Street Journal that police on Wednesday evening were interviewing a "person of interest" in connection with the fire but the individual had not been charged.

Wilson did not immediately return a call or email.

Black churches in the US South have long been a base of support for the Democratic Party.

During the US civil rights movement of the 1950s and 1960s, southern black churches were often targets for arson and bombings by white supremacists.

"The FBI Jackson Division is aware of the situation in Greenville, and we are working with our local, state and federal law enforcement partners to determine if any civil rights crimes were committed," the agency said in a statement.

"This act is a direct assault of people's right to freely worship," Greenville Mayor Errick Simmons said in a statement.

The town of some 33,000 people is about 100 miles (160 kms) northwest of Jackson.

"The act that happened left our hearts broken," Pastor Carolyn Hudson told the news conference, noting that the church has a 111-year history.

The Mississippi Republican Party declined to comment.

In October, the Orange County Republican Party's office in Hillsborough, North Carolina, was set on fire and a graffiti message left nearby said "leave town or else."

No arrests have been made in that incident, which Indiana Governor Mike Pence, the Republican vice presidential candidate, called "political terrorism."