Israel allowed only 12 people to enter Egypt through Gaza's Rafah border Monday, the first day of a limited reopening for the besieged Palestinian territory's only access to the outside world.

"Five injured people and seven companions" crossed the border, a source told Agence France-Presse (AFP) on Tuesday.

The reopening, demanded by the United Nations and aid groups, is a key part of the second phase of U.S. President Donald Trump's truce plan for Gaza, where humanitarian conditions remain dire after two years of war.

The number of patients allowed to enter Egypt through the crossing was limited to 50 Monday, each accompanied by two companions, according to three officials at the Egyptian border.

An Egyptian health official told AFP on Monday that three ambulances had arrived with Palestinian patients who were screened upon arrival to determine which hospital to be taken to.