Authorities in Afghanistan say they have foiled an alleged plot to assassinate President Hamid Karzai.

Afghanistan's intelligence agency said Wednesday six suspects have been arrested, including some who allegedly were trained in Pakistan's North Waziristan tribal region.

A spokesman for Afghanistan's National Directorate of Security (Lutfullah Mashal) says a “dangerous and educated group” included teachers and students and one of Mr. Karzai's bodyguards.

Authorities say the would-be assassins allegedly were in contact with an Egyptian and a Bangladeshi who are members of al-Qaida and the Haqqani network based in Pakistan. Officials also said the plotters had access to $150,000 to fund their activities.

The French news agency quoted an unnamed Afghan government official as saying intelligence agents were still searching for others allegedly involved in the plot, including teachers, students, civil servants and a journalist.

Mr. Karzai has been the target of at least three assassination attempts since becoming Afghanistan's leader in 2002. The president rarely leaves the closely guarded palace compound in Kabul, since surviving a 2008 attempt on his life at a military parade in the Afghan capital.

Wednesday's announcement also follows a series of high-profile killings, including the Jassassination in July of the president's powerful half-brother, Ahmad Wali Karzai – killed 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 during a strike in the Musa Khel district on Tuesday. A statement said 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, who was captured one week ago.

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