Members of an American special-forces team have been disciplined after an inquiry into the death of a British aid worker in Afghanistan found that U.S. military law had been breached, the U.K. foreign secretary said Thursday.

Linda Norgrove died in October following a botched attempt by U.S. special forces to free her in Afghanistan's Kunar province, where she was abducted in an ambush. Officials initially said Norgrove was slain by her captors, but U.S. Gen. David Petraeus later acknowledged that a U.S. grenade may have killed her.

William Hague told British lawmakers that the joint U.S.-U.K. investigation confirmed a grenade thrown by U.S. forces had killed Norgrove. The operation to free her was carried out in complete darkness, and an officer threw the grenade in the direction of insurgents out of fear for his life, he said.

Military law was violated when special forces failed to immediately report the use of a device to military higher-ups, Hague said.

The foreign secretary deferred to U.S. officials on details on the number of individuals involved and how they were reprimanded, but he said hostage-rescue tactics were undergoing a review in the U.S. to ensure greater accuracy and transparency in wake of similarly complicated operations.

"Senior British military officers have been briefed on the results of the investigation and will ensure that the lessons learned from this operation are shared," Hague added.

Despite the revelations, the foreign secretary defended the decision to launch the "incredibly difficult" rescue operation, saying authorities feared for Norgrove's life and judged a rescue attempt as the only "credible" way to secure her release.

The family of Linda Norgrove thanked the U.K. and U.S. militaries for briefing them in detail on the findings of the inquiry, saying in a statement they will comment in more detail next week after taking time to digest the contents of the report.