Donald Trump on Thursday signed an executive order on religious liberties designed to ease a ban on political activity by churches and other tax-exempt institutions.

The order also mandates regulatory relief to religious employers that object to contraception, such as Little Sisters of the Poor.

It does not include provisions to allow government agencies and businesses to deny services to gay people in the name of religious freedom, as was feared by some civil liberties and gay rights groups.

The American Civil Liberties Union said in a statement it would file a lawsuit challenging Trump's order.

Trump, addressing religious leaders in a signing ceremony at the White House, said: "We will not allow people of faith to be targeted, bullied or silenced any more".

"No one should be censoring sermons or targeting pastors," he said.