The Saudi embassy in Islamabad has been in contact with the Haqqani Network, a Sunni Islamist organization that operates along the Pakistan-Afghanistan border and is considered the most lethal and sophisticated group targeting U.S. and Afghan forces, documents released by WikiLeaks reveal.

According to one of the cables published by WikiLeaks, the former Saudi ambassador in the Pakistani capital Islamabad, Abdul Aziz Ibrahim Saleh Al Ghadeer, met with Nasiruddin Haqqani, the son of the terrorist group’s leader and founder Jalaluddin Haqqani, reports Pakistan Today.

The meeting reportedly took place on February 15, 2012.

Amb. Ghadeer arranged for the the Haqqani Network’s leader to go into Saudi Arabia to receive medical treatment, the leaked documents show.

An Afghan television station reported that Saudi officials contacted the Haqqani Network with the help of the U.S.

“The classified documents show that Jalaluddin Haqqani has held Saudi Arabia’s citizenship, but they do not specify the date of Haqqani’s visit to Saudi Arabia,” said Afghanistan’s Tolo TV in Dari, according to a translation by BBC. “The documents show that Saudi officials have had contacts with leaders of the Haqqani Network with the help of CIA.”

A separate cable, dated February 25, 2012, reveals that the Saudi ambassador was made aware of the Haqqani leader’s ailment. Nevertheless, the document does not mention the disease by name.

Citing local media accounts, Pakistan Today notes that Jalaluddin Haqqani, who would have been 62 years old in 2012, was suffering from either Parkinson’s disease or Lupus. The Haqqani leader was reportedly based in Waziristan, Pakistan in 2012.

Jalaluddin Haqqani was a known associate of al-Qaeda founder Osama Bin Laden, reports the U.S. National Counterterrorism Center (NCTC). He was considered one of Bin Laden’s “closest mentors” during the 1980s anti-Soviet war in Afghanistan, described by NCTC as the formative years of the mastermind of the 9/11 attacks against the U.S. homeland.

Saudi Arabia’s Foreign Ministry has expressed concern about WikiLeaks’ release of tens of thousands of documents. However, it has said that the leaked information does not contradict Riyadh’s known foreign policies.

“The venue of the [February 2012] meeting has not been mentioned, but the ambassador usually held meetings either at the embassy or his residence, both of which are located in the heavily guarded Diplomatic Enclave and remains under the watchful eyes of Pakistani intelligence agencies, says the cable,” Pakistan Today reports.

The Haqqani Network has been designated as a foreign terrorist organization by the United States. It is considered the most dangerous terrorist group targeting American troops in Afghanistan.

“The Haqqani Network is primarily based in North Waziristan, Pakistan, and conducts cross-border operations into eastern Afghanistan and [Afghan capital] Kabul,” notes NCTC. “The group is primarily composed of members of the Zadran tribe. The Haqqanis are considered the most lethal and sophisticated insurgent group targeting U.S., Coalition, and Afghan forces in Afghanistan, and typically conduct coordinated small-arms assaults coupled with rocket attacks, IEDs [Improvised Explosive Devices], suicide attacks, and attacks using bomb-laden vehicles.”

The terrorist group has been linked to al-Qaeda and the Taliban.