The power supply to the Hamas-administered territory was cut by almost a third after the Palestinian Authority cut payments for electricity supplied by Israel, arguing that Hamas is not paying its share of the cost.
Egypt sent fuel on Wednesday to the Gaza Strip's only power plant to help alleviate an energy crisis as two million residents in the Palestinian enclave get less than three hours of electricity per day.
Israel has cut the power supply by almost a third after the Palestinian Authority stopped paying Israel for electricity, arguing Hamas is not reimbursing its share of the cost.
Diesel tankers, flying the Egyptian and Palestinian flags, crossed into the Gaza Strip two days after Israel began cutting back on its electricity feed to the area.
The one-million-litre shipment on Wednesday could be followed by another delivery of the same amount later on Thursday, the Hamas-appointed deputy finance minister in Gaza, Youssef al Kayali,said.
The delivery was the first official import of Egyptian diesel to Gaza since Hamas took over the enclave in 2007.
It could provide seven hours of power for three days.
Gaza's Hamas chief, Yehya Al-Sinwar, and Egyptian security officials agreed on imports at talks in Cairo this month. Sources close to those negotiations said the deal was also facilitated by Mohammad Dahlan, a Fatah rival of Abbas, living in Abu Dhabi.
Fuel from Egypt used to be smuggled through tunnels, many of them now destroyed by Cairo, which said they were conduits for weapons and militants battling Egyptian forces in the neighbouring Sinai Peninsula.
Hamas has denied the allegation.
Health services under threat
Gaza's power plant has been offline for two months due to a payment dispute between the Palestinian Authority, based in the Israeli-occupied West Bank, and Gaza's Hamas.
Any worsening of the energy crisis could cause the collapse of health services, local health officials said.
Hospitals largely rely on generators for power, as do Gaza residents who can afford the high cost of fuel.
Palestinian President Mahmoud Abbas's decision to cut the payments was coupled with calls from Palestinian officials for Hamas to relinquish control of Gaza, which Hamas seized from fighters loyal to Abbas's Fatah movement in 2007.