The US Secret Service says agents have intercepted packages containing "possible explosive devices" addressed to former President Barack Obama and Hillary Clinton.

The agency says neither Clinton nor Obama received the packages, and neither was at risk of receiving them because of screening procedures.

It says the devices were discovered late Tuesday and early Wednesday.

A US official tells The Associated Press that a "functional explosive device" was found during screening at Bill and Hillary Clintons' suburban New York home.

The official says investigators believe the explosive is linked to one found Monday at the compound of liberal billionaire George Soros.

The Secret Service says a second package was addressed to Obama and was intercepted in Washington.

Meanwhile, reports said that suspicious package similar to those addressed to Barack Obama and Hillary Clinton were also found at CNN's New York bureau.

According to reports, New York Police received information about a suspicious package at Time Warner Center, where the CNN bureau is located. The building was evacuated and cops were seen conducting sanitisation operations. 

White House condemns act as 'despicable'

The White House condemned attempted attacks on Obama, Clinton, others, and said that 'these terrorizing acts are despicable'.