A senior Afghan official says al-Qaida militants based in Pakistan were behind a recent assassination attempt on President Hamid Karzai in Kabul.

Afghan Intelligence Chief Amrullah Saleh said Sunday that al-Qaida's involvement in the April 27 attack is, in his words, "very clear."

Afghan Defense Minister Abdul Rahim Wardak says authorities have arrested two Afghan government employees on suspicion of helping the attackers. He says one suspect worked in the defense ministry and the other in the interior ministry.

Afghanistan has long called on Pakistan to destroy al-Qaida bases on the Pakistani side of their common border. Pakistan says it does all it can to fight al-Qaida and other militants who infiltrated its territory after the U.S.-led invasion of Afghanistan in 2001.

Afghanistan's Taliban movement has claimed responsibility for the attack.

President Karzai escaped unharmed when the attackers opened fire on a military parade in Kabul, but three bystanders were killed. Afghan troops later shot dead three gunmen.

The Associated Press quotes Defense Minister Wardak as saying the detained defense ministry worker allegedly provided AK-47 assault rifles to the gunmen.

Afghan security forces raided the hideout of a key suspect in Kabul last Wednesday, triggering a battle that killed him and six other people. Intelligence chief Saleh says the suspect, known as Humayun, also was involved in a suicide attack on a Kabul hotel in January that killed eight people.

Some information for this report was provided by AFP, AP and Reuters.