As Pakistan's civilian leadership falters under the weight of challenges from the army and the judiciary, a resurgent hard-line movement is making a noisy comeback.

Difa-e-Pakistan or Defence of Pakistan is an alliance of extremist right-wing groups - some of which are banned - formed after a Nato air strike killed 24 Pakistani soldiers late last year.

In recent weeks these groups and their supporters have been marching in their thousands across Pakistan's major cities. And the clerics at the helm of this reinvigorated hard-line movement are some of the biggest names in Pakistan's jihadi network, prompting calls of concern from US officials.

Maulana Fazlur Rahman Khalil is one of those clerics. Surrounded by a jostling crowd of his supporters in a Karachi restaurant, he looked smaller than in the many images of him one sees emblazoned on posters. But he has always cast a large shadow over Pakistan's militant circles.

Militant forefathers

He is a founder and, some say, still the head of the militant jihadi group Harkatul Mujahideen, formed at the end of the Soviet-Afghan war and known for its links with al-Qaeda.

He denies it exists any more saying it came to an end after the Afghan jihad. But when confronted with claims that there is overwhelming evidence of its continued existence, he burst out laughing.

Instead, he is keen to highlight the teachings of his current group, Ansar-ul Umma, which he says exists to inform Pakistan about "American belligerence".

Image caption Maulana Khalil was said to be very close to al-Qaeda

"It has has been tiring. We've been going around the city for the last two days," he says.

Maulana Khalil is a wanted man, on a US terror watch list. But in recent days he has been busy rallying for support before a major meeting of the new alliance. Such rallies are part of his and Difa-e-Pakistan's campaign to become a significant political force. But it does not take much to expose the militant credentials of its members.

The alliance includes groups like Jamaat-ud-Dawa and Ahle-Sunnah Wal Jamaat. Security officials say they are just aliases for well-known banned militant groups such as Lashkar-e-Taiba and Sipah-e-Sahaba and, of course, Maulana Khalil's own Ansar-ul Umma is accused of being front for Harkatul Mujahideen. They are all held responsible for thousands of deaths in militant attacks.

Officials say that these new names are clever subterfuge, which allow these groups protection from the authorities and the courts as no cases are registered against the new names.

If we had still been up in arms, would we be giving press conferences Maulana Khalil

But Maulana Khalil is eager to point to the legitimacy of these groups, saying: "All parties here including the Ansar-ul-Umma are legitimate bodies with no bans on them."

Police protection?

The official police protocol and display of automatic weapons by members at the Difa-e-Pakistan rallies also suggests greater forces at play.

Pakistan's government says its hands are tied because court orders that allow banned groups to operate under new names. But the evidence of state involvement is everywhere. Indeed some of the activists talk openly about support from the shadowy intelligence establishment.

Local police officials even stood up and saluted Maulana Mohammad Ahmed Ludhiavi, head of the Sipah-e-Sahaba militant group. Maulana Khalil strongly denies there is anything wrong with this.

"We are just protesting. If we had still been up in arms, would we be giving press conferences?" he says.

Image caption Maulana Khalil and Osama Bin Laden were closely allied during the Soviet- Afghan war

Past evidence suggests otherwise. In 1998, along with a little known Saudi militant commander, Maulana Khalil signed a fatwa declaring war on the West.

The declaration was called the International Front Against Jews and Crusaders and the Saudi was Osama Bin Laden. It set the tone for the international jihadi movement, which set the stage for the 9/11 attacks.

He declines to talk about the fatwa these days, saying: "I'll discuss it if you can produce a copy of the fatwa."

Analysts say that Maulana Khalil is still close to the Haqqani militant network - singled out by the US last year for spearheading attacks on US forces in Afghanistan and he is also believed to have trained several high-profile militants, such as Ilyas Kashmiri and Badar Mansoor, both recently killed by US drone strikes in north-west Pakistan.

If they have clear proof that we are terrorists - that we have killed innocent people - we are willing to suffer whatever punishment Maulana Khalil

And after Osama Bin Laden's death the US media reported that recovered data from his hideout indicated the al-Qaeda chief was still in contact with Maulana Khalil.

Maulana Khalil, however, laughs it off: "All I can say is if a list was made of those making such accusations on me - America would always be on top."

He does not deny having a close relationship with al-Qaeda's leader, but says they were last in contact at the end of the Afghan jihad.

"We say that if they have clear proof that we are terrorists - that we have killed innocent people - we are willing to suffer whatever punishment," he says.

Public support

The crucial question is the level of public support this movement has. The leaders are clearly keen to present themselves as a legitimate voice and insist their new groups operate within the law. They have a website and even have a presence on Twitter and are trying to gather funds on the ground.

Image caption Religious parties did poorly at Pakistan's last elections

But they mostly hope to capitalise on Pakistanis' growing disillusionment with mainstream political parties. This is also felt in the government's perceived inability to stand up to the US, which in the eyes of some Pakistanis, is responsible for the deaths of Pakistani civilians in drone strikes.

Such feelings are driving support for people like Maulana Khalil.

While he talks flanked by his followers, young madrassa students peer into the glass windows of the restaurant to catch a glimpse of their beloved leaders.

"I just want to do their ziarat," says one wide-eyed boy not more than 10 years old. Ziarat means pilgrimage and for those young men meeting Maulana Khalil is nothing less than that.

Religious parties did poorly in Pakistan's last election. It is not yet clear how and when Difa-e-Pakistan plans to put itself to the public popularity test. For the moment, it appears content to gather momentum.