A new wave of bomb threats against Jewish community centers across the United States and in Canada have prompted lock-downs and evacuations, as federal authorities investigate a surge of threats against Jewish organizations in recent months.

The reported threats were phoned in or emailed to Jewish community centers in states including New York, Wisconsin, Illinois and Florida on Tuesday.

Jewish centers in the Canadian province of Ontario, including the provincial capital of Toronto, also said they were threatened.

"We’ve never seen such a period of concentrated threats against the Jewish community," New York Mayor Bill de Blasio told a news conference. "The last few weeks are more troubling than anything I’ve seen in many, many years."

Authorities have been investigating the surge of threats against the organizations, including more than 100 hoax bomb threats in five separate incidents in January and February.

The White House on Tuesday denounced the newest round of threats. In his first speech to the US Congress last week, President Donald Trump condemned the anti-Semitic incidents.

Also on Tuesday, all 100 members of the US Senate asked the federal government to help enhance security in Jewish community centers.

Jewish community centers and schools in the United States have received five waves of hoax bomb threats since the beginning of this year, which has prompted fears of an increase in anti-Semitism.

It is not clear what triggered the reported surge in anti-Semitic attacks.

Last week, the Jewish Agency for Israel, the largest Jewish organization in the world, expressed “deep concern” over the recent wave of attacks.

The agency, however, was itself involved in supporting Zionist terrorist groups in the occupied Palestinian territories.

Toppled headstones remain on the ground at Washington Cemetery in the New York borough of Brooklyn on March 5, 2017. (Photo by AFP)

The agency supported early Israeli terror groups, including the Irgun, the Lehi and the Haganah, which have carried out numerous violent attacks against Palestinians and Jews, as well as citizens from other countries.

Irgun and Lehi were described as terrorist organizations by the United Nations, American and British governments, and in media such as The New York Times newspaper.