Save the Children on Monday said it was looking into Israeli claims that a Palestinian staff member in Gaza had been recruited by Hamas, days after allegations against another international NGO.
"We do take any allegations of this nature very seriously and are making inquiries into this matter," the Britain-based charity said in a statement.
It comes after Israel on Thursday charged the Gaza head of major international NGO World Vision Mohammed al-Halabi with diverting millions of dollars in foreign funding to Hamas and its military wing.
Part of it was allegedly used to build attack tunnels from the blockaded territory into Israel.
Halabi was arrested in June and indicted on a number of charges, which his lawyer said were baseless.
According to the charge sheet, Halabi recruited a Palestinian aid worker from Save the Children to join Hamas's military wing, the Ezzedine al-Qassam Brigades, in 2014.
It said that Ezzedine al-Qassam Brigades wanted that individual because of "connections" between Save the Children and USAID, the United States Agency for International Development.
The Hamas military wing wanted him to supply them with information about individuals placed in international organisations in Gaza by the United States, said the charge sheet.
The Palestinian aid worker was listed as the official Save the Children contact for two programmes carried out in 2014 which were worth $1 million and $1.4 million respectively.
AFP contacted the man but he declined to make any comment.
Save the Children said in its statement it had "not been notified or contacted by the (Israeli) authorities on the details of the allegations."
According to a UN tracking service, Save the Children has received more than $17 million from international donors since 2013 for its humanitarian aid activities in the occupied Palestinian territories.
Canada, Denmark, Japan and Norway are among its major donors.
On Monday the United Nations expressed "serious concerns" over the World Vision allegations.
