Investigators have begun interrogating two Al Qaeda (search) suspects and three Afghans arrested in northwestern Pakistan, hoping for clues to other top operatives of the terror group, including Usama bin Laden (search), officials said Thursday.

The alleged members of Al Qaeda — Adil Al-Jazeeri from Algeria and Abu Naseem from Tunisia — were arrested late Tuesday in Peshawar (search), the capital of Pakistan's deeply conservative North West Frontier Province where a pro-Taliban religious coalition rules.

The three Afghans also were arrested in Peshawar this week, Interior Ministry official Brig. Javed Iqbal Cheema told The Associated Press. They are also suspected of involvement with Al Qaeda.

Security agencies stepped up their pursuit of Al-Jazeeri after receiving information that he was planning attacks in Pakistan.

"It was not easy to confirm the identification of Adil Al-Jazeeri," an intelligence official familiar with the investigation told AP on condition of anonymity. "We're doing some tough questioning now," he said without elaborating.

Al-Jazeeri frequently traveled between Peshawar and major Pakistani cities. Authorities are trying to learn more about his alleged activities.

A security official, who also spoke on condition of anonymity, said they were "cross-checking" information provided to them by Al-Jazeeri and Abu Naseem, who was arrested in a separate raid near an Afghan refugee camp on the western edge of the city.

Naseem was said to be an expert in forgery and arranging fake documents for Al Qaeda.

The men are being held by Pakistan and questioned by Pakistani police, but the United States has been informed of the arrests, Cheema said.

Pakistan is a key ally of the U.S.-led war on terror, and its security agencies have arrested nearly 500 suspected Al Qaeda members since the war in neighboring Afghanistan was launched in response to the Sept. 11, 2001, terrorist attacks in America.