The gathering in Bangladesh was second in size only to the annual Hajj pilgrimage to Mecca in Saudi Arabia.

The event, known as Biswa Ijtema is organised by World Tablig Jamaat, an organisation of Islamic preachers who teach austerity and devotion to God.

Osama bin Laden is rumoured to have attended last year

But this year police have been put on alert after unconfirmed reports that supporters of the suspected Islamic militant Osama bin Laden could be among the crowds.

"We are keeping close watch especially on the foreign delegates," said a federal Police official.

Assassination attempt

The news comes after police arrested over 40 Bangladeshi Muslims last week on charges of trying to assassinate the country's leading poet, Shamsur Rahman.

Those arrested are reported to have admitted links with Osama bin Laden, who is suspected by Washington of masterminding last year's US embassy bombings in Africa.

During questioning, the suspects told police that they belong to Harakat-ul-Jihad, a little-known Islamic group reportedly linked with the Taleban fighters in Afghanistan, bin Laden's home for many years.

No worldly comfort

Bangladesh is far from the Middle Eastern centres of international Muslim pilgrimage and many of its people pride themselves on their secular tradition.

But according to correspondents, given that Bangladesh is the world's ninth most populous country, with more than 130 million people, the vast majority of whom are Muslims, it is not surprising that the meeting has become the world's second biggest Islamic gathering in terms of numbers.