US President Donald Trump has threatened to disarm Hamas "violently" amid moves by the group to reassert control over the Gaza Strip, targeting what it called "collaborators".

Speaking to reporters on Tuesday, Trump said if Hamas failed to disarm within "a reasonable period of time" then "we will disarm them". He did not say when he expects the group to surrender its weapons.

His comments came as footage circulated online showing a public execution and other displays of force by Hamas fighters in Gaza since the US-brokered ceasefire began last week.

The execution - which BBC Verify geolocated to a junction in central Gaza City - follows Hamas's pledge to crush "lawlessness" in the Strip.

Other verified clips have shown armed men wearing insignia identifying them as members of Hamas's internal security force on patrol and masked fighters firing on unarmed men.