JERUSALEM, March 13 — An up-to-date Israeli government register shows that 32.4 percent of the property held by Israeli settlements in the occupied West Bank is private, according to the advocacy group that sued the government to obtain the data.

The group, Peace Now, prepared an earlier report in November, also provided to The New York Times, based on a 2004 version of the Israeli government database that had been provided by an official who wanted the information published. Those figures showed that 38.8 percent of the land on which Israeli settlements were built was listed as private Palestinian land.

The data shows a pattern of illegal seizure of private land that the Israeli government has been reluctant to acknowledge or to prosecute, according to the Peace Now report. Israel has long asserted that it fully respects Palestinian private property in the West Bank and takes land there only legally or, for security reasons, temporarily. That large sections of those settlements are now confirmed by official data to be privately held land is bound to create embarrassment for Israel and further complicate the already distant prospect of a negotiated peace.

The new data, updated to the end of 2006, was provided officially by the Israeli government’s Civil Administration, which governs civilian activities in the territories, in response to a lawsuit brought by Peace Now and the Movement for Freedom of Information in Israel in 2005. When the courts refused the request, the groups filed an appeal, and the earlier data was leaked to Peace Now. In January, the court ordered the Civil Administration to provide the data, in the form of digitized map information.