Media playback is unsupported on your device Media caption Mohammad Ibrahim: "We teach our pupils religion, we don't preach extremism in this madrassa"

The US Treasury earlier this week imposed economic sanctions on a Pakistani Islamic school - or madrassa - in the city of Peshawar which it described as a "terrorist training centre" providing support to al-Qaeda and the Taliban. But after a recent visit, the BBC's M Ilyas Khan says that at first glance the seminary hardly evokes suspicions.

It is a three-storey building spread over approximately 500 square yards. There are no open spaces, no shooting ranges and no parade grounds.

The surrounding buildings are equally cramped and devoid of privacy.

The endless, winding alleyways of this neighbourhood meander around its tightly knit clusters of houses and are too narrow for vehicular traffic.

As such, the Madrassa Taleemul Quran wal-Sunnah - a religious seminary located on the eastern outskirts of the north-western city of Peshawar - seems an unlikely militant training centre.

On Tuesday, the US Treasury said that students at the madrassa, under the guise of religious studies, have been "radicalised to conduct terrorist and insurgent activities".

'Insult to the intelligence'

But officials at the madrassa vehemently deny this.

"Our doors are open, see for yourself, we even invite the Americans to come and have a look," says Qari Mohammad Ibrahim, the principal of the seminary.

"There isn't enough space for the classrooms, much less for a training centre."

Image caption Seminary officials say there are about 120 students - aged between 10 to 18 - enrolled at the school

The ground floor of this narrow, oblong building contains a mosque and a separate area for washing and ablutions.

The first floor is a long hall, with a single wooden bookshelf running along the length of its four walls.

In a corner in the eastern part of the hall, mattresses, pillows and blankets are stacked against a wall.

The hall serves as a classroom by day and a dormitory by night.

There are about four rooms on the top floor, which are used as classrooms for higher grades.

Seminary officials say there are about 120 students enrolled at the school, of whom at least 40 are resident scholars. Most of them are between 10 and 18 years of age.

"It is a place for religious learning, and that's what we do. To say that this place can be used to train terrorists is an insult to the intelligence of those who have seen it," says Haji Alam Sher, the 83-year-old founder of the seminary.

Aggressive recruiters

So why did the Americans single it out for sanctions?

Some circles speculate that it may be because it is the only main centre for a hard-line Salafist sect of Muslims in Peshawar.

It is a radical sect that considers jihad, or holy war, as more central to its religious ideology than many other sects.

Being a minority among the religious groups both in the Middle East and Pakistan, the Salafists have been more aggressive recruiters and fundraisers.

The Salafi group in Pakistan, Lashkar-e-Taiba, emerged as the largest and most effective jihadist outfit to fight in Indian-administered Kashmir and also in Afghanistan.

A source familiar with the management of Peshawar's Madrassa Taleemul Quran wal-Sunnah says Jamatud Dawa, a successor organisation of Lashkar-e-Taiba, has also been using the premises as its main centre in the area.

The seminary first hit the headlines in 2009 when one of its top clerics, Shaykh Aminullah Peshawari, was designated by both the US and the UN for "providing material support to al-Qaeda and the Taliban".

The students and teachers at the seminary are quite vague in their answers when asked about his whereabouts.

'Influential' Salafist

Mr Sher says Mr Peshawari resigned and left eight months ago. But others say he may have been around until more recently.

Image caption Madrassa founder Haji Alam Sher denies any links at all to terrorism

Mr Sher is also reluctant to tell me how long Mr Peshawari served at the seminary, saying: "Only God may know, I have no knowledge of it."

But another official tells me in confidence that Mr Peshawari, originally a resident of Afghanistan's north-eastern province of Kunar, was a co-founder of the seminary, established in the late 1980s.

A fluent Arabic speaker, Mr Peshawari is believed to have had influence both with the Arab fighters in Afghanistan and charity donors in the Middle East.

Now in his late-40s, he started out in the late 1980s as a member of a former Afghan mujahideen group close to the Salafist thinking.

Despite being an influential Salafist ideologue, he is also considered close to Taliban who mostly belong to the Deobandi sect of Islam and have religious differences with the Salafists.

Mr Peshawari's followers in north-eastern Afghanistan reportedly enjoy smooth relations with the local Taliban there and have been co-ordinating their activities with them.

There are credible reports that Mr Peshawari has been using the Peshawar seminary as a recruitment centre and also as a transit point for Salafist fighters involved in fighting against Nato forces in Afghanistan's north-east.

The Americans have also accused him of directing "donations provided for the school to terrorist groups such as the Taliban".

While the management of the seminary insists he left several months ago, one of his followers who regularly attended his Friday sermons told me in confidence he left only last month, to go on a pilgrimage to Mecca.

An official of the seminary admitted this in an off-the-record conversation.

"Mr Peshawari was in Saudi Arabia last month and later returned to Rawalpindi where he was preaching at a well-known (Salafist) mosque until the Muslim festival of Eid on 9 August," he said.