BUSAN: US Secretary of State Hillary Clinton said on Wednesday she regretted Pakistan's decision to boycott next week's international conference on Afghanistan but hoped to secure Islamabad's cooperation in future.

“Nothing will be gained by turning our backs on mutually beneficial cooperation. Frankly it is regrettable that Pakistan has decided not to attend the conference in Bonn,” Clinton told a news conference in South Korea.

Pakistan pulled out of the conference on the future of Afghanistan on Tuesday in reaction to a cross-border attack by Nato that killed 24 of its soldiers and plunged US-Pakistani relations deeper into crisis.

“I would express regret and hope that perhaps there can be a follow-up way that we can have the benefit of Pakistani participation in this international effort to try to work a stable, secure peaceful outcome in Afghanistan.”

Clinton stressed that US officials were making every effort to investigate what she called a “tragic incident”.

“What is most important I think is that we learn lessons from this tragedy because we have to continue to work together.”