Beijing has explained its restrictions on the Hadj by stating it is a very dangerous undertaking, with high risks of being trampled, though a more likely explanation is that Beijing simply cannot control what happens outside its borders.

Below are extracts from an article published by BBC:

At dusk in the city of Kasghar, you can shoot your enemies one-by-one at one of the arcade games set up in the main square.

The sun has gone down. Dozens of old men walk towards the Id Kah mosque just off the square.

This is a Muslim city. The people who live here are Central Asian - they are known as Uighurs. They have their own language and culture.

But China's ruling Communist Party is everywhere.

It picks Kashgar's rulers, it sends in Chinese soldiers to patrol the nearby border with Afghanistan, and it even makes sure the city's clocks are set to Beijing time.

The communists want the Uighur people to understand one thing - their province is an inseparable part of China.

My colleague and I stop a couple of young women in the main square.

"Where we're standing in Kashgar - is this China?" I ask.

"Yes," they both reply quickly. And they say nothing more.

Everybody else we ask gives the same answer. It is not surprising - speaking out against the Communist Party in China is dangerous.

[…]

Some of China's worries are written on the walls of Kasghar.

[…]

[One sign reads:] "Organising your own group pilgrimage [to Mecca] is illegal."

By the side of the road, my colleague and I start talking to a Uighur man selling cups of tea and bowls of mutton soup.

[…]

Later on, we join a tour of the Id Kah mosque.

A jumpy Chinese government guide tells us not to disturb the Muslims at prayer.

A local Uighur guide tries to explain the Communist Party's ban on unofficial group pilgrimages to Mecca.

"If you organise a group to go to Mecca by yourself, it's illegal because you're not taking care of the group's safety," he explains.

"If they go to Mecca they might be trampled or killed by other people because there are too many people inside the mosque."

But there is another reason for the ban. The Communist Party does not want young Uighur men getting together where they cannot be controlled.

The Communist Party is suspicious of the power of religion.

And there is something strange about Kashgar - it is a Muslim city, but there are no loud calls to prayer.

A government official assures us that we have simply not been listening properly, and that the evening call to prayer from the Id Kah mosque will soon be heard loud and clear.

But the minutes go by. Then the official explains that the call to prayer will not happen because the loudspeaker at the mosque has just broken.

China prefers less threatening sounds. So, a trade fair in the provincial capital of Urumqi is opened with a burst of non-religious, non-political folk music.

Inside the main building, Communist Party chiefs - officials, soldiers and bodyguards - wander through the exhibits.

Nurlan Abdumajin, a deputy governor of Xinjiang, says: "Our principle is clear - if there are separatists, we will get them. No matter how many of them there are.

"The unity of China is our responsibility. That's what the people want. This province is very secure now."

And China wants it to stay that way.