PLANTATION - A man suspected of sending at least 14 mail bombs to prominent critics of US President Donald Trump in the run-up to next month's national elections was arrested on Friday in Florida and charged with five federal felonies.

Cesar Sayoc, 56, was taken into custody outside an auto parts store in Plantation, Florida, near Miami. Authorities seized a white van belonging to him, the windows of which were plastered with pro-Trump stickers, the slogan "CNN SUCKS" and images of Democratic politicians with red cross-hairs over their faces.

Fingerprint and DNA evidence was used to identify Sayoc, but Federal Bureau of Investigation Director Christopher Wray cautioned that his arrest did not necessarily end the threat.

"There may be other packages in transit now and other packages on the way," Wray said.

One federal law enforcement source told Reuters that authorities were still investigating whether other individuals were involved and did not rule out the possibility of more arrests.

Sayoc's arrest followed an intense four-day-old manhunt for whoever was responsible for at least 14 pipe bombs mailed to high-profile Democrats and others known as outspoken critics of Trump, including former US President Barack Obama and former Secretary of State Hillary Clinton, who Trump defeated in the 2016 presidential race.

The first of the bombs surfaced on Monday at the Westchester County, New York, home of billionaire Democratic donor George Soros. Four packages turned up on Friday, the 14th being addressed to a major contributor to the Democratic Party, Tom Steyer in San Francisco.

Each consisted of explosive material packed in a plastic pipe and wired to a small clock and a battery, Wray said.

All the bombs were intercepted before reaching their intended targets and without exploding, and no one has been hurt.

The bombs have heightened tensions during what was already a highly contentious campaign season ahead of the Nov. 6 elections in which Democrats are battling to seize control of Congress now held by Trump's Republican Party.

Reuters