New York Gov. Andrew Cuomo speaks during the New York gubernatorial debate hosted by CBS 2 and WCBS Newsradio 880. File picture: Mary Altaffer/AP Photo.

New York - New York's Democratic governor Andrew Cuomo announced that a suspicious device was also sent to his office in Manhattan, after apparent pipe bombs were sent to CNN and Hillary Clinton's home in the state.

"A device has been sent to my office in Manhattan," Cuomo told a news conference. "The device sent to my office has been identified and is being handled as we speak."

The governor, who is a trenchant critic of US President Donald Trump and who is seeking a third term as chief executive of the country's fourth most populous state, said he "wouldn't be at all surprised" if more devices show up.

Cuomo's revelation comes after US Senator Kamala Harris's staff confirmed that their San Diego offices were evacuated Wednesday after suspicious packages were found nearby. 

City police however, however confirmed the boxes were harmless.

The downtown building, which also contains the offices of the San Diego Union-Tribune newspaper, was evacuated "out of an abundance of caution" when someone noticed five boxes stacked up outside, but X-ray tests confirmed the contents posed no threat, San Diego Police Department Lieutenant Kevin Wadhams told KUSI television.

The false alarm comes amid a series of discoveries of suspicious packages mailed to Democratic politicians, including suspected explosive devices sent to former president Barack Obama and defeated presidential nominee Hillary Clinton, as well as to CNN's New York bureau.