Israel's Foreign Ministry has launched a campaign meant to put a spotlight on the suspected funneling of millions of dollars in aid to Hamas's military wing.
Mohammad El Halabi, the manager of operations in Gaza for the NGO World Vision, was arrested by the Shin Bet on June 15 while crossing the border into the enclave.
A senior Israeli security official on Thursday said Halabi, who has run the group's Gaza operations since 2010, had been under extended surveillance and had confessed to siphoning off some $7.2 million a year to Hamas.
World Vision said it was shocked by the claims and a Hamas spokesman said the group had no connection with Halabi.
After news of the allegations came to light, the Foreign Ministry instructed all of its missions worldwide to work to bring the story to the attention of world media, opinion makers and senior officials in the different branches of government.
The Israeli diplomats were asked to emphasize Israel's humanitarian aid to the Strip and its facilitation of the reconstruction of Gaza, as well as the obligation of governments and international organizations to monitor the humanitarian aid they send to the Palestinian enclave.
Specifically, the diplomats were instructed to spread the news of the Halabi's alleged actions among liberal and religious groups who support World Vision.
"Contacts, journalists and relevant opinion makers should be briefed, and an emphasis needs to also be put on the digital arena," senior Foreign Ministry officials instructed.
The diplomats were equipped with detailed background materials about the case and talking points to be used in meetings, posts on social media, and infographics.
Foreign Ministry Director-General Dore Gold also sent a letter to his counterparts in the world to update them on the case.
"The investigation uncovered a lot of information concerning other figures in Gaza who took advantage of their position in humanitarian aid organizations and UN institutions on behalf of Hamas," Gold wrote.
"It's important to note that Hamas has close ties to the security apparatus in Iran, which is looking for ways to expand its military influence from Syria to Yemen. Beyond that, Hamas has also been closely working with ISIS militants in northern Sinai. The bolstering of Hamas's military abilities—made possible by humanitarian aid—serves the strategic interests of the big destabilizing powers operating in the Middle East today."
Meanwhile, Australia decided to suspend funding for World Vision's operations in the Palestinian Territories in the wake of the allegations.
Australia's Department of Foreign Affairs and Trade (DFAT) called the allegations "deeply troubling" and said in a statement that it was "urgently seeking more information from World Vision and the Israeli authorities."
"We are suspending the provision of further funding to World Vision for programs in the Palestinian Territories until the investigation is complete," it said.
Australia has paid World Vision approximately A$5.7 million ($4.35 million) over the past three financial years for the provision of aid in the Palestinian Territories, a DFAT spokesman said.
Reuters contributed to this report.