WASHINGTON -- U.S. Sen. Cory Booker, touring a refugee camp in the Middle East, called on the U.S. to do more to help those fleeing the Syrian civil war and address "a humanitarian crisis of a scale rarely witnessed in the last 50 years."

Booker (D-N.J.) in a telephone interview with NJ Advance Media, called for both more aid to refugee camps in the Middle East and for the U.S. to take in more Syrians in addition to the 10,000 already committed to. He said three million people have been displaced.

"America should do its part in taking more refugees," Booker said. "This is a humanitarian crisis of a scale rarely witnessed in the last 50 years."

The senator spoke in the middle of an official visit to Iraq, Qatar, Jordan and Israel, where he was meeting with U.S. ambassadors and government officials. He said went to the region because "there are so many issues stemming from areas of the Middle East that are crucial to the safety" of the state and the nation.

Syrian refugees are screened for 18 to 24 months before being allowed to enter the U.S., making any threat "incredibly slim," Booker said.

"For all the ways to enter this country now, the waiver program would be one of the last ways someone would choose to get into the country," Booker said.

His comments contrast with those of Republican presidential nominee Donald Trump, who has called for banning Muslims from entering the U.S. and a temporary moratorium on admitting refugees from certain regions.

In addition, the Republican-controlled House voted in November to require additional background checks before admitting Syrian refugees.

And Gov. Chris Christie said last fall that New Jersey would not accept any more Syrian refugees.

Booker made his comments after visiting the largest United Nations refugee camp in the region, located in Amman, Jordan, and home to tens of thousands of Syrian refugees.

He also called for more aid to countries like Jordan who are housing the refugees, most of whom want to return to their homes in Syria once the fighting ends.

"These are folks who are just looking for safety and security," he said. "Right now, the entire globe has a responsibility. It's a level of suffering that is really unconscionable."

Before returning to the U.S., Booker also was traveling to Israel to meet with officials there. He called the visit "a continuance of my long-term commitment" to Israel.

Booker's biggest lifetime donor is the Englewood Cliffs-based pro-Israel political action committee NORPAC, which has raised or donated $158,871 for his Senate campaigns, according to the Center for Responsive Politics, a Washington-based research group.

He broke with NORPAC President Ben Chouake and voted for the agreement that ended economic sanctions in exchange for curbs on Iran's nuclear program for more than a decade.

After Congress failed to block deal, Booker co-sponsored legislation making it official U.S. policy that all options, including military action, remain available to prevent Iran from obtaining a nuclear weapon.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant. Find NJ.com Politics on Facebook.