The Washington based government is deemed to raise further questions over Pakistan’s unwillingness to carry out an onslaught against militant using its base to target Afghanistan. This issue would also be weighed against the restoration of NATO supplies within the Afghani region.

The “attack issue” erupted days after Pakistan's parliament finally approved new guidelines for the country in its relationship with the US, a decision that Washington hopes will pave the way for the reopening of supply lines to NATO troops in Afghanistan.

Pakistan halted NATO operations by closing its border crossing amid American strikes at the Salala camp that resulted in the martyrdom of 24 Pakistani soldiers. . It has taken the government months to navigate the delicate path of reinstating ties with the U.S., a difficult process in a country where anti-American sentiments are extensive.

The attacks were the most widespread in Kabul since an assault on the U.S. Embassy and NATO headquarters last September also blamed on the Haqqani network. US officials accused Pakistan's Inter-Services Intelligence agency (ISI), of assisting that attack, sparking outrage in Islamabad.

An ISI official said Monday that claims the Haqqani network was behind the latest attacks were "nothing but accusations."

"We have no idea who carried out these attacks," the official said, speaking on condition of anonymity because he was not authorized to talk to the media. "Whenever something happens, blame is always laid on our doorstep."

If the role of the Haqqani network is confirmed, it could place the Obama administration in a tricky position. It could face pressure from Congress and Republican presidential contender Mitt Romney to criticize Pakistan.

The relationship is further complicated by Pakistani opposition to US drone strikes targeting the Haqqani network and other militants along the border. Pakistan's parliament has demanded the attacks stop, but the US has refused to comply.

Washington has long demanded that Pakistan target Taliban militants and their allies in the Haqqani network who are using Pakistani territory to launch cross-border attacks against American troops in Afghanistan.

One of the militants arrested during the latest attacks in Kabul and three other cities has told authorities that the Haqqani network was behind the assaults, Afghan Interior Minister Besmillah Mohammadi said Monday.

A spokesman for NATO forces in Afghanistan, Lt. Col. Jimmie Cummings, said they were still trying to determine who carried out the attacks.

"A Haqqani connection is a possibility, but still too early to determine for sure," Cummings said.