Image caption The Pakistani Taliban is said to be closely linked to the Haqqani network

The US is to designate the Pakistan-based militant Haqqani network as a terrorist organisation, subjecting it to sanctions.

US Secretary of State Hillary Clinton said she had sent a report to Congress saying the network met the criteria as a terror group.

She said the US would continue "diplomatic, military and intelligence pressure on the network".

The US has long described the Haqqani group as a major threat.

The network - which has links to al-Qaeda and the Taliban - has carried out a series of high-profile attacks against foreign troops in Afghanistan.

The designation will ban companies and individuals in the US from supporting the group and freeze any US assets it may have.

State department officials said the formal designation would be made in the coming days.

"Today, I have sent a report to Congress saying that the Haqqani network meets the statutory criteria of the Immigration and Nationality Act (INA) for designation as a Foreign Terrorist Organisation (FTO)," said Mrs Clinton, who is currently attending an Apec (Asia-Pacific Economic Co-operation) summit in Vladivostok, Russia.

"We also continue our robust campaign of diplomatic, military and intelligence pressure on the network, demonstrating the United States's resolve to degrade the organisation's ability to execute violent attacks."

Mrs Clinton added that she was taking the action "in the context of our overall strategy in Afghanistan" following policy laid out by US President Barack Obama when he visited Afghanistan in May.

The Pentagon said the Haqqani network "represents a significant threat to US national security and we will continue our aggressive military action against this threat".

"These new group designations will build on our efforts to degrade the network's capacity to carry out attacks, including affecting fundraising abilities, targeting them with our military and intelligence resources, and pressing Pakistan to take action," said George Little, the acting Assistant Secretary of Defence for Public Affairs.

Hostage fears

In response to the US move, senior commanders of the Haqqani network told Reuters news agency that the decision showed the US was not sincere about peace efforts in Afghanistan.

They also said the move would "bring hardship" for US army sergeant Bowe Bergdahl, 25, who has been held prisoner for more than three years.

The Haqqanis also hold numerous Western, Pakistani and Afghan hostages as well as kidnap-for-ransom victims.

The US has been putting pressure on Pakistan to launch a ground offensive in North Waziristan, where the Haqqanis are based, but Pakistan is reluctant.

The BBC's Jill McGivering says that any such offensive would probably be focused on disrupting the Pakistani Taliban - an internal threat - and not on attacking the Haqqanis, whose battleground is Afghanistan.

The US fears that Islamabad sees the Haqqanis as potential allies after Nato's withdrawal from Afghanistan, she says.

Last year, US Admiral Mike Mullen, former head of the US military, said the Haqqani network had become a "veritable arm" of Pakistan's Inter-Services Intelligence (ISI) agency.

Analysts say this prompted suggestions that a designation against the Haqqanis would indirectly be branding Pakistan a terrorist state.

In Washington, the White House has also been under political pressure from Congress to add the Haqqanis to the country's terrorist blacklist.

Congress had set Mrs Clinton a deadline of this weekend to deliver her report.

Meanwhile, the US has been disrupting the group, targeting leaders in drone attacks.

Last month, an air strike in North Waziristan was reported to have killed a key Haqqani commander, Badruddin Haqqani.

He had been described as a senior operational commander, masterminding and directing attacks on high-profile targets.

Correspondents say he was also responsible for training camps and for extorting funds from contractors.