KABUL, Afghanistan  — Five NATO-led service members were killed in a helicopter crash in southern Afghanistan on Saturday, the coalition forces said in a statement. A statement said the helicopter crashed due to unspecified "technical problems."

"ISAF is still in the process of reviewing the circumstances to determine more facts," the International Security Assistance Force said. It did not provide details of the service members' nationalities.

Foreign forces casualties have fallen in the past few months, as U.S.-led forces start to wind down operations ahead of a year-end deadline to leave Afghanistan.

The United States has been at odds with President Hamid Karzai who has refused U.S. entreaties to sign a bilateral security agreement that would permit about 8,000 U.S. troops to remain in the country after the formal U.S. withdrawal at the end of the year.

The leading contenders to replace Karzai have, however, said they will sign the agreement to allow the small contingent of U.S. forces to stay in the country for counter-terrorism and Afghan training purposes.

Since the start of the year, at least 24 foreign civilians, including doctors and journalists, have been killed in a series of attacks across the country.