Washington, Jun 7 (IANS): Homeland Security Secretary John Kelly has said that the current blocking of President Donald Trump's "travel ban" has been limiting the US' ability to keep "potential wrong-doers" out of the country.

In a testimony before the Senate Homeland Security Committee, Kelly on Tuesday insisted that he was "not fully confident" that the government was doing everything possible to keep "dangerous" people out of the country, Efe news reported.

Trump had signed an executive order earlier in 2017 banning citizens from six Muslim-majority nations -- Iran, Somalia, Sudan, Syria, Yemen and Libya -- from entering the US.

However, a Federal court had stopped the ban from being implemented.

"Bottom line, I've been enjoined from doing these things that I know would make Americans safe, and I anxiously await the court to complete its action one way or the other so I can get to work," Kelly told lawmakers.

Kelly said that the court injunction on the executive order has prevented his department from temporarily forbidding US entry to citizens of these nations that were either involved in civil war or were state sponsors of terrorism.

He also noted that these countries were the same ones that the Congress had singled out in 2015 as nations of concern.

"It has nothing to do with religion, or skin colour or the way they live their lives, but all about security for the US, nothing else," Kelly said.

"These are countries that (are) either unable or unwilling to help us validate the identities or backgrounds of persons within their borders."

In Syria and Iraq, he warned, there were thousands of jihadists who have come from more than 120 countries, and -- as the US-led coalition advanced in battle against them -- many of them were returning to Europe, South Asia, Southeast Asia, Australia and the Western Hemisphere.

The US authorities felt that some were trying to enter the US to carry out terrorist attacks and Trump had this in mind when he issued the executive order banning their citizens, Kelly said.

After the London terror attack on Saturday, Trump once more insisted that his travel ban must be implemented.

The first version of the ban was blocked by the courts, whereupon the administration issued a revised version of it on March 6 that is now under review by the Supreme Court.

The Department of Justice has argued that Trump, as President, has full authority to decide how to protect US national security and to prohibit -- as the second version of the ban sets forth -- US entry to refugees for 120 days and to citizens of the six nations for 90 days.

The second version of the ban, in contrast to the first one, did not include citizens of Iraq and modified the provision on Syrian refugees.