Israeli security forces have broken up 13 Hamas terrorist cells in the West Bank since May, according to a report released this week by the Meir Amit Intelligence and Terrorism Information Center.

The cells were in various stages of preparing for terrorist attacks and operated mostly in the cities of Hebron and Jerusalem. As a result of the exposures, dozens of Hamas operatives have been detained.

Israeli security officials arrested dozens of people just last week in connection with the murder of a British tourist and with an attempted suicide bombing.

"Interrogation of the detainees showed that their main objective was to kidnap Israeli citizens for bargaining," the report said. "Also planned were mass murder terrorist attacks, one of which was actually carried out [in March 2011]…Other operations planned by the cells were thwarted and the operatives were detained."

Interrogation of the detainees showed that the cells were directed and logistically supported by Hamas headquarters in Syria and the Gaza Strip. Saudi Arabia was the location for recruitment meetings and instructions from Hamas members there were transferred to operatives in Hebron.

"The exposure of these terrorist cells shows that Hamas headquarters are engaged in intensive efforts to rebuild the movement's military infrastructure in Judea and Samaria [the West Bank] for the purpose of launching terrorist attacks against Israel," according to the report.

In a speech Friday, Palestinian Authority President Mahmoud Abbas pledged to seek full membership for a Palestinian state next week at the United Nations Security Council. U.S. officials have pledged to veto the move.

"It is possible that the motivation to carry out terrorist attacks has even increased (and may increase still) ahead of the PA's application to the UN," the report adds.