Afghan officials say authorities have foiled an alleged plot to assassinate President Hamid Karzai.

Afghanistan's intelligence agency said Wednesday they arrested six suspects, including some who allegedly receiving training in Pakistan's North Waziristan tribal region.

National Directorate of Security spokesman Lutfullah Mashal says a “dangerous and educated group” including teachers and students with ties to al-Qaida and the al-Qaida-linked Haqqani network was behind the plot. He added the group was able to recruit one of President Karzai's bodyguards.

Mr. Karzai has been the target of several assassination attempts since becoming Afghanistan's leader in 2002.

Wednesday's announcement also follows a series of high-profile killings, including the July assassination of the president's powerful half-brother Ahmad Wali Karzai by a security guard at his home in the southern city of Kandahar.

U.S. and Afghan officials increasingly have accused the Haqqani network of conceiving and carrying out attacks in Afghanistan with the support of Pakistan's military spy agency, a charge Islamabad denies.

Earlier Wednesday, NATO officials said a coalition airstrike killed a senior Haqqani network leader in southeastern Khost province near the border with Pakistan.

The militant, known only as Dilawar, was killed Tuesday during the strike in the Musa Khel district. A statement says two of his associates were also killed in the strike.

NATO says Dilawar was a “principal subordinate' to Haji Mali Khan, the main leader of the Haqqani network in Afghanistan. It says he died exactly one week following Khan's capture.

The alliance accuses Dilawar of working with Khan to plan attacks against Afghan and coalition forces along the border area. The statement adds that he was also responsible for facilitating the movement of foreign fighters and weapons in the area.