The United States says it is close to deciding whether to label the Pakistan-based Haqqani network a foreign terrorist organisation.
Secretary of State Hillary Clinton said a final review was under way before making a decision on the group blamed for a series of attacks in Afghanistan.
US officials say the group was behind the recent attack on the US embassy in Kabul in which some 25 people died.
They have been putting pressure on Pakistan to sever links with the group.
The most senior US military officer, Adm Mike Mullen, recently accused Pakistan's spy agency of supporting the Haqqani group, an allegation Pakistani officials deny.
The spat has further strained US-Pakistan ties which have deteriorated sharply since the killing of al-Qaeda chief Osama Bin Laden on Pakistani soil by US commandos in May.
Adm Mullen's comments have caused uproar in Pakistan and there are calls for an end to security co-operation with the US, the BBC's Aleem Maqbool in Islamabad reports.
Political and religious parties, convened by the prime minister, are meeting in Rawalpindi to discuss ties with the US. It is the largest such gathering in years, our correspondent says.
"We're in the final, formal review that has to be undertaken to make a government-wide decision to designate the network as a foreign terrorist organisation," Mrs Clinton told a news conference in Washington on Wednesday.
She said seven leaders of the group had been placed under US sanctions since 2008.
The Haqqani network, which is closely allied to the Taliban and reportedly based in Pakistan, has been blamed for several high-profile attacks against Western, Indian and government targets in Afghanistan.
It is often described by Pakistani officials as a predominantly Afghan group.
But correspondents say its roots reach deep inside Pakistani territory, and speculation over its links to Pakistan's security establishment refuses to die down.
US officials have long been frustrated at what they perceive to be Pakistani inaction against the Haqqani network, and analysts say US concern about the group's capabilities is particularly acute as Nato begins withdrawing troops from Afghanistan.
After Adm Mullen's accusation last week, Pakistan's government warning that the US could lose Pakistan as an ally if it continued to publicly accuse Islamabad of supporting militants.
Foreign Minister Hina Rabbani Khar has said that the US cannot afford to alienate Pakistan's government or its people.
Washington, however, has kept up the pressure, urging Islamabad to break any links it has with the Haqqani network.
Pakistan denies its intelligence service has links with the Haqqani network and says it is determined to fight all militants based on its border with Afghanistan.