Pakistan will boycott an international conference on the future of Afghanistan in Germany next week to protest against a NATO cross-border attack that killed 24 of its soldiers and plunged the region deeper into crisis, officials said on Tuesday.

The decision not to attend the conference, aimed at bringing all major stakeholders together in securing a peaceful Afghanistan after NATO combat troops leave at the end of 2014, will likely rattle policymakers from Washington to Kabul.

Pakistan has decided not to attend the Bonn conference as a protest, a government official told Reuters after a cabinet meeting chaired by Prime Minister Yusuf Raza Gilani in Lahore.

A second government official, who also asked not to be identified, confirmed the decision.

One fear is that Pakistan might seek to pursue its own interests in Afghanistan, disregarding those of its allies in the West and elsewhere.

The decision appears to be the latest attempt by Pakistan to put pressure on the United States, Afghanistan and NATO.

Pakistan says NATO staged an unprovoked attack on two combat outposts early on Saturday that killed 24 Pakistani troops and wounded 13.

NATO described the killings as a tragic, unintended incident. U.S. officials say a NATO investigation and a separate American one will seek to determine what happened. The U.S. investigation will provide initial findings by December 23, military officials said.

U.S. State Department spokesman Mark Toner said on Monday Washington hoped Pakistan would still attend the conference.

(Reporting by Augustine Anthony and Mubasher Bukhari; Writing by Chris Allbritton; Editing by Paul Tait)