Israel has charged a senior World Vision employee with providing support to the Hamas movement, the organisation has announced.

World Vision is the world's largest evangelical Christian charity and has operated in Israel-Palestine for more than 40 years.

Its manager of operations in Gaza Mohammad El Halabi was arrested on June 15 at a checkpoint on his way home from what World Vision says were "routine meetings" and spent 50 days in detention. He has now been charged with supporting Hamas, which governs Gaza and is regarded as a terrorist movement by Israel and some other countries, including the US. He has been head of the Gaza branch of World Vision since 2010 and has worked for the organisation since 2005. However, Israel alleges he has been a Hamas operative since 2004.

According to Israeli newspaper Haaretz, the Shin Bet (one of Israel's security services) is accusing El Halabi of being a member of Hamas' armed wing, Izzedin al-Qassam, and of having infiltrated World Vision. Shin Bet also alleged that $80,000 worth of donations from British people have been diverted to pay for Hamas-related activities.

El Halabi's lawyer, Mohammed Mahmoud, strongly denied any wrongdoing. "Israel can link anyone living in the Gaza Strip to Hamas. Mohammed does not belong to the organisation nor is he affiliated with Hamas," he said.

World Vision said it was "shocked to learn of these charges against Mohammed". In a statement, it said: "World Vision subscribes to the humanitarian principles of impartiality and neutrality and therefore rejects any involvement in any political, military or terrorist activities and maintains its independence as a humanitarian aid agency committed to serving the poor, especially children. World Vision has detailed procedures and control mechanisms in place to ensure that the funds entrusted to us are spent in accordance with applicable legal requirements and in ways that do not fuel conflict but rather contribute to peace."

It said its Gaza programmes were regularly audited internally and independently. It said of the charges: "Based on the information available to us at this time, we have no reason to believe that the allegations are true. We will carefully review any evidence presented to us and will take appropriate actions based on that evidence."

A previous statement said: "World Vision stands by Mohammad who is a widely respected and well regarded humanitarian, field manager and trusted colleague of over a decade. He has displayed compassionate leadership on behalf of the children and communities of Gaza through difficult and challenging times, and has always worked diligently and professionally in fulfilling his duties."

World Vision's Jerusalem offices were raided by police after Halabi's arrest. The Shin Bet said, "We weren't investigating the organisation, but rather Hamas activists. We have no suspicions against the organisation."

Gaza's Christian population is tiny, at around 1,200 people out of a total of 1.8 million.