Explosive devices were found at the offices of former secretary of state Hillary Clinton in New York and former president Barack Obama in Washington, the Secret Service said on Wednesday.

The Secret Service, the law enforcement agency that protects current and former US governmental officials, said it intercepted the two suspicious packages.

The one sent to Clinton was found at her home in Westchester County New York, the agency said in a news release. The package addressed to Obama was intercepted by Secret Service personnel in Washington, it said.

"The packages were immediately identified during routine mail screening procedures as potential explosive devices and were appropriately handled as such," the release said.

Neither Clinton nor Obama were at risk of receiving the packages, the Secret Service said.

The Secret Service is investigating to determine who sent the packages.

The devices were similar to one found on Monday at the home of the billionaire philanthropist George Soros.

Soros' foundation on Tuesday attacked the "hateful rhetoric" dominating US politics after the suspicious package was found.