RAWALPINDI, Pakistan (REUTERS) - Pakistani police fired tear gas on Monday to disperse crowds of supporters of a prominent anti-government cleric who was due to arrive in the country to lead a self-proclaimed revolution against Prime Minister Nawaz Sharif.

A Reuters reporter at the scene said about 2,000 supporters of Mr Tahirul Qadri, who is usually based in Canada, clashed with police outside an airport near the capital Islamabad where the cleric had been due to land at 7 am (10 am, Singapore time) on Monday.

Amid chaotic scenes at Benazir Bhutto International Airport, it was not immediately clear if his plane had landed as planned.

Police cordoned off major roads leading to the airport with cargo containers and blocked mobile phone services to prevent protesters from communicating with each other.

Mr Qadri, who champions religious tolerance and once issued a fatwa against the Taleban, is a divisive figure in Pakistan where he made headlines last year when he led mass rallies against the previous government.

His sudden ascent to prominence has prompted speculation that the military, which ruled Pakistan for decades, may be using him as a proxy in its efforts to sideline the civilian government.

"Long live the army!" and "Revolution will come!" chanted his supporters who had gathered outside the airport in the military garrison city of Rawalpindi near Islamabad.

In remarks issued on the eve of his expected return, Mr Qadri said he was ready to lead a "revolution" against the government and praised the army.

His reappearance comes at a tense time in Pakistan after the army announced an all-out offensive against militants on the Afghan border, triggering a wave of refugees from the region.

Mr Sharif, who was once toppled by the military and has an uneasy relations with the army, has long been opposed to military action and the decision to send troops there was seen as a major win for the army.