JERUSALEM - Israel said Tuesday it had charged a United Nations staffer with helping the Islamist movement Hamas, the second indictment involving aid workers in Gaza in a week.

Engineer Waheed Borsh, who has worked for the UN Development Programme (UNDP) since 2003, was arrested on July 16 and charged in a civilian court in Israel on Tuesday, a government statement said.

The UNDP said it was "greatly concerned" by the allegations while Hamas, which has run the Gaza Strip since 2007, denied any involvement.

The government said 38-year-old Borsh, from Jabaliya in northern Gaza, had been recruited by "a senior member of the Hamas terrorist organisation to redirect his work for UNDP to serve Hamas's military interests".

It said he had confessed to a number of accusations, including diverting rubble from a UNDP project in the coastal strip to a Hamas operation to build a jetty for its naval force.

He is also alleged to have last year persuaded UNDP managers to focus home rebuilding efforts in areas where Hamas members lived, after pressure from the group.

More than 11,000 homes were completely destroyed in Gaza during Israel's war with Hamas and other factions in the summer of 2014, according to the United Nations.

No figures were provided on how much aid Borsh allegedly diverted and the charge sheet provided by the justice ministry did not say he joined Hamas.

The UNDP said it was "greatly concerned by the allegation," promising in a statement "a thorough internal review of the processes and circumstances surrounding the allegation."

Despite the claims, the statement said, the UN remained confident it had "robust measures in place" to prevent aid diversion.

Hamas labelled the allegations "incorrect and baseless".

In a statement it said they were part of a wider Israeli effort "to tighten the siege of the Gaza Strip by prosecuting international relief organisations."

Since 2008, Israel has fought three wars in Gaza with Hamas, which is branded a terrorist organisation by Israel, the United States and the European Union.

Israel has long alleged that aid has been diverted to Hamas, claims rejected by NGOs and the United Nations.

Aid workers privately admit to pressure from Hamas.

But they say materials and goods taken into Gaza are subject to some of the strictest monitoring in the world and say Israel uses concerns around Hamas as an excuse to restrict import of basic goods into the enclave.