Darren Cormack, the chief executive of Mines Advisory Group, said: "Our colleague was conducting an explosive hazards assessment at a Unops building when the incident happened.
"He has now been evacuated to a hospital in Israel.
His condition is not known." The Israeli army denied striking a UN building in Gaza.
But it came as Israel launched a ground operation to recapture a key corridor cutting through the middle of Gaza, deepening its renewed offensive in the war-torn territory.
Tel Aviv shattered the ceasefire with Hamas on Tue...