Pakistan ? Suicide attacks have killed nearly 1,200 people in Pakistan since July 2007, most of them civilians, according to military statistics Monday that underscored the ferocity of the threat facing the U.S. ally in the war on extremist groups.

Meanwhile, heavy fighting between Pakistani troops and insurgents in the lawless tribal regions of the country’s northwest has caused some 20,000 Pakistanis to flee across the border into Afghanistan, the United Nations said.

Nuclear-armed Pakistan has seen a surge in attacks by Islamic extremists since the July 2007 army attack on militants holed up in Islamabad’s radical Red Mosque, during which about 100 people were killed.