Israel's military admitted Saturday it had fired on ambulances in the Gaza Strip after identifying them as "suspicious vehicles," with Hamas condemning it as a "war crime" that killed at least one person.

The incident took place last Sunday in the Tal al-Sultan neighbourhood in the southern city of Rafah, close to the Egyptian border.

Israeli troops launched an offensive there on 20 March, two days after the army resumed aerial bombardments of Gaza following an almost two-month-long truce.

Israeli troops had "opened fire toward Hamas vehicles and eliminated several Hamas terrorists," the military said in a statement to AFP. 

"A few minutes afterward, additional vehicles advanced suspiciously toward the troops... The troops responded by firing toward the suspicious vehicles, eliminating a number of Hamas and Islamic Jihad terrorists." 

The military did not say if there was fire coming from the vehicles. 

It added that "after an initial inquiry, it was determined that some of the suspicious vehicles... were ambulances and fire trucks," and condemned "the repeated use" by "terrorist organizations in the Gaza Strip of ambulances for terrorist purposes."

The day after the incident, Gaza's civil defence agency said in a statement that it had not heard from a team of six rescuers from Tal al-Sulta who had been urgently dispatched to respond to deaths and injuries. 

On Friday, it reported finding the body of the team leader and the rescue vehicles — an ambulance and a firefighting vehicle — and said a vehicle from the Palestine Red Crescent Society was also "reduced to a pile of scrap metal."

Basem Naim, a member of Hamas's political bureau, accused Israel of carrying out "a deliberate and brutal massacre against Civil Defense and Palestinian Red Crescent teams in the city of Rafah." 

"The targeted killing of rescue workers — who are protected under international humanitarian law — constitutes a flagrant violation of the Geneva Conventions and a war crime," he said.  

Tom Fletcher, head of the United Nations Office for the Coordination of Humanitarian Affairs, said that since 18 March, "Israeli airstrikes in densely populated areas have killed hundreds of children and other civilians."

"Patients killed in their hospital beds. Ambulances shot at. First responders killed," he said in a statement. 

"If the basic principles of humanitarian law still count, the international community must act while it can to uphold them."