Florida records show that Sayoc has a lengthy criminal record in the state, including a 2002 arrest for a bomb threat and others for larceny and fraud. MSNBC reported that he was a registered Republican.

His social media profiles are littered with bizarre messages threatening liberal donors and media outlets, and photos from a Trump rally in 2016. He describes himself as a booking agent at Hard Rock casino and a former wrestler, cage fighter and professional soccer player.

Rita Katz, director of SITE Intelligence Group, said a review of social media pages didn't indicate affiliation with far-right extremist organisations but show "an intense support" for Trump as well as Islamophobic sentiments and the promotion of conspiracy theories

Shortly after the arrest, Trump called the suspected mail bombs "terrorising acts" and praised law enforcement officers.

"We will prosecute them, him, her, whoever it may be, to the fullest extent of the law," he said at a White House event. "We must never allow political violence to take root in America and I'm committed to doing everything in my power as president to stop it and stop it now."

However, just before Sayoc was taken into custody, Trump posted a tweet that seemed to question the timing and veracity of the bomb scares.

The arrest came hours after two more suspicious packages were found on Friday - one addressed to Democratic Senator Cory Booker of New Jersey and another to former national intelligence chief James Clapper, another frequent target of criticism from the far right.

The former was intercepted in Florida, the latter at a mail sorting facility on New York City's Upper West Side.

The packages were similar to 10 other crude pipe bombs mailed to prominent Democrats and liberal supporters, and progressively discovered in sorting facilities and mail boxes since Monday.

None of the devices have exploded.

The first package was detected on Monday at the New York home of billionaire philanthropist and Democrat donor George Soros.

Since then, packages have been intercepted that were addressed to Obama, Hillary Clinton, Biden, former CIA director John Brennan, actor Robert De Niro, Congresswoman Maxine Waters, former Attorney-General Eric Holder, Senator Kamala Harris, Clapper and Booker.

Booker, Harris and Holder are all potential 2020 presidential contender.

At a press conference on Thursday, officials in New York would not discuss possible motives or details on how the packages found their way into the US postal system. Nor would they say why none of the packages had detonated, but they stressed they were still treating them as "live devices".

"As far as a hoax device, we're not treating it that way," Commissioner James O'Neill said.

Details suggested a pattern - that the items were packaged in manila envelopes, addressed to prominent Trump critics, carried US postage stamps and had the same return address for Florida-based Democratic Congresswoman Debbie Wasserman Schultz. The devices were being examined by technicians at the FBI's forensic lab in Quantico, Virginia.

The packages stoked nationwide tensions and fears as voters prepared to vote November 6 to determine partisan control of Congress - a campaign both major political parties have described in near-apocalyptic terms. Even with the sender still unknown, politicians from both parties used the threats to decry a toxic political climate and lay blame.

"A very big part of the Anger we see today in our society is caused by the purposely false and inaccurate reporting of the Mainstream Media that I refer to as Fake News," Trump said on Twitter on Thursday.

"It has gotten so bad and hateful that it is beyond description. Mainstream Media must clean up its act, FAST!"

with AP