US President Donald Trump on Wednesday said it should be known within three weeks whether Hamas will agree to give up its weapons, and threatened action if the group does not.

"That's what they agreed to. They've got to do it. And we're going to know ... over the next two or three days - certainly over the next three weeks - whether or not they're going to do it," Trump said in a question and answer session following his speech at the World Economic Forum in Davos.

"If they don't do it, they'll be blown away very quickly. They'll be blown away."

This is a developing story.