The decision to withhold millions of dollars in annual aid is linked to US anti-terrorism legislation.
The US has confirmed it stopped all aid to Palestinians in the occupied West Bank and Gaza, in a step linked to new anti-terrorism legislation.
More than $60m (£46m) in annual funds for the Palestinian security services has now ended, and - while Israel has backed some previous cuts in US aid for Palestinians - officials have expressed concern about this move.
It is thought that co-operation with Israeli forces, which helps keep relative calm in the West Bank, could be affected.