The armed wing of Gaza’s terror group Hamas said Thursday it would stop receiving fundraising via the cryptocurrency Bitcoin, citing an increase in “hostile” activity against donors.

Izz el-Deen al-Qassam Brigades, the Palestinian enclave’s most powerful armed faction that has fought several wars with Israel over the years, said the move “comes out of concern about the safety of donors and to spare them any harm,” adding that it had seen an increased effort to prevent people and groups from sending it Bitcoin funds.

The group also renewed its call for “continued donation to Qassam and the resistance by all available means.”

Gaza economist Mohammad Abu Jayyab told Reuters the decision implied that Hamas feels as though Israel could reveal the identities of donors or reach their wallets, and were therefore seeking to protect them.