US lawmakers on Wednesday (18 November) called for even tighter scrutiny of Syrian refugees fleeing to the US as last week's deadly Paris attacks recast America's debate over immigration and national security.

The move prompted a sharp rebuke from President Barack Obama, who said that attempts to block entry were offensive and contrary to American values.

Republican leaders in the US House of Representatives, worried about attacks after 129 people were killed by terrorists in Paris, threatened to suspend the Obama administration's efforts to allow 10,000 more Syrian refugees into the country.

The issue has challenged the US' image of itself as a nation that welcomes downtrodden newcomers, with some lawmakers suggesting all Syrians should be barred, or that Christian Syrians should be favoured over Muslims.

Obama, speaking on the sidelines of the Asia-Pacific Economic Cooperation Summit in Manila early on Wednesday, accused politicians at home of trying to score political points.

"We are not well served when, in response to a terrorist attack, we descend into fear and panic. We don't make good decisions if it's based on hysteria or an exaggeration of risks," he said, occasionally showing flashes of anger.

"I cannot think of a more potent recruitment tool for Isil than some of the rhetoric that's been coming out of here during the course of this debate," he said, using another name for Islamic State.

Obama said refugees are screened for 18 to 24 months before being cleared to enter the US, with the intelligence community fully vetting applicants.

"When candidates say we should not admit three-year-old orphans, that's political posturing. When individuals say we should have religious tests, and only Christians, proven Christians, should be allowed, that's offensive and contrary to American values."

Other Western countries have begun to question their willingness to admit Syrians after reports that at least one of the Paris attackers passed through Greece in October.