Image copyright Mohammad Hoseini

Downstairs in the busy cafe at the School of Oriental and African studies in central London, Anahita, a student, is working behind the bar.

She was born in the UK but grew up mainly in Iran, and prefers not to use her surname after being arrested in Tehran for taking part in demonstrations there.

Yet here, Anahita has had to face other challenges. Being lesbian has not been an issue with her contemporaries in London.

However, she tells me that being a Shia Muslim here has sometimes proved harder.

With many Islamic Societies at British universities mostly under Sunni leadership, the sectarian divides so bitterly apparent in much of the Middle East between the Sunni majority and the Shia minority are making themselves felt here in the UK.

Right now, there is talk in the Sunni community that Shia are not Muslims Sheikh Ahmed Haneef, Islamic Centre for England

The two main branches of Islam emerged following the death of the Prophet Muhammad, in 632, and a battle for influence across the Middle East between mainly Sunni Saudi Arabia and Shia-dominated Iran is involved in much of the conflict.

"Even at Soas, a university I love, Sunnis and Shias have big arguments all the time," says Anahita.

"And elsewhere in London, we have the same problem - Sunni and Shia arguing. You can clearly see it when you walk in Edgware Road or Kilburn.

"If you have a green bracelet or anything that shows you are Shia, they look at you as if you are not even Muslim, or you don't exist. It's very disrespectful, and very sad.

"Islamic societies in general and especially in London are getting bigger all the time. But not in a good way."

University radicalism

Anahita says despite that, she has many Sunni friends.

But her fears echo those of others, who worry about the role played by some Islamic societies at Britain's universities since it first emerged that some British Muslims were being radicalised while studying.

Last week, the University of Westminster came under renewed scrutiny when an Islamic Society event due to be held on Thursday featuring a controversial Islamic preacher was postponed after one of the university's former students, Mohammed Emwazi, was identified as the man wielding the knife in Islamic State's most brutal videos.

Image copyright Mohammad Hoseini Image caption Anahita, left, says there are arguments between Sunni and Shia students

So do other Muslims notice increasing tensions between Sunni and Shia in the UK?

Very much so, according to Sheikh Ahmed Haneef, an imam who preaches at the Islamic Centre for England, a Shia mosque in Maida Vale in west London.

The ornate white mosque building used to be a Mecca bingo hall before the Shia community refurbished it. He says the divides are becoming ever more apparent.

"It's quite stark in universities, and you can't go into a Sunni mosque and pray with a piece of clay or with your hands down by your side, which is one of the main minor differences between us.

"We wouldn't dare do that in a Sunni mosque. I think as the kids grow in religiosity, they tend to get infected by this kind of attitude. Right now, there is talk in the Sunni community that Shia are not Muslims."

He adds that worshippers have also noticed a shift in attitude.

Security fears

Ahmed Haneef worries about security at the mosque, pointing out that Islamic State sees Shia Muslims as the enemy, and have called on supporters to attack them.

"Our mosque is very prominent, and I think we should be very careful. One guy came and broke the glass doors outside."

He dates the starting point for real tensions between Sunni and Shia outside the Middle East to 1979, after the revolution in Iran.

I don't necessarily know if the tensions have spilled over from the Middle East, as essentially that's 1,400 years' worth of disagreement Sadaf Rasheed, Oxford University student

"I think from that point we see the ramping up of anti-Shia rhetoric in the Sunni mosques, exacerbated by the fact that Saudi Arabia was putting a lot of investment into the training of imams and the building of mosques.

"They represent what started as a minor branch of Islam that was intolerant, so the spread of this form of what we call Wahhabism took off in the 1970s and increased in vitriol.

"I don't want to sound sectarian, but there is a growing distance, on the Sunni side, because on the Shia side we don't have the same rhetoric."

Haneef says he's keen for more initiatives here to bring the two communities together before the divide becomes dangerous.

Sunni divisions

So what about Sunni students? Sadaf Rasheed, 23, is from east London, and is studying for a Masters degree at Oxford University.

Sadaf believes that the bigger divides in the UK are within Sunni Islam, rather than between Sunni and Shia.

"I don't necessarily know if the tensions have spilled over from the Middle East, as essentially that's 1,400 years' worth of disagreement," she says.

"I see more inter-Sunni conflict, though Sunni-Shia conflict does happen, particularly in Islamic societies - it is quite prevalent.

"We've constructed the idea that they are 'other' to us, and I think to an extent both parties are to blame. Personally, I have a lot of Shia friends."

What are the differences between Sunnis and Shia?

Image copyright AP Image caption Pilgrimage to Mecca is one of many rituals that are shared by both Sunni and Shia Muslims

Muslims are split into two main branches, the Sunnis and Shia. The split originates in a dispute soon after the death of the Prophet Muhammad over who should lead the Muslim community.

The great majority of Muslims are Sunnis - estimates suggest the figure is somewhere between 85% and 90%.

Members of the two sects have co-existed for centuries and share many fundamental beliefs and practices.

Though they may not interact much outside the public sphere, there are always exceptions. In urban Iraq, for instance, intermarriage between Sunnis and Shia was, until recently, quite common.

The differences lie in the fields of doctrine, ritual, law, theology and religious organisation.

Their leaders also often seem to be in competition.

At Leicester Central Mosque, Dr Ather Hussain al Asri - a Sunni Imam and writer - also believes that the increase in tensions here is caused by a particular strand of Sunni Islam.

"Wahhabism is very small in terms of its numbers, but unfortunately in terms of finances, Wahhabi Islam is very strong in this country and that is because they are getting direct funding from the Middle East.

"So what they lack in numbers, they are making up for it in terms of organisation. Unfortunately, they are operating in universities and through social media, and they prey on the vulnerability of our youth."

Both imams say that Sunni and Shia have co-existed in peace in the UK and elsewhere in the past, and both warn that the main victims if sectarianism here worsens will be Muslims themselves.