Post-9/11 many Indian filmmakers experimented with the theme of terrorism. But filming them on foreign soil has become an uphill task, especially in Britain.

If writer-director Renzil D'Silva had his way, his debut film on terrorism, which is being produced by Karan Johar, would have been shot in London. Unfortunately permission was denied to shoot in any underground tube station of London.

The same happened with Karan's directorial venture "My Name Is Khan". He couldn't get permission to shoot this Shah Rukh Khan and Kajol starrer in London. Finally, Karan too shot in the US his film about the isolation of the Muslims after 9/11.

A little ironical, considering Jagmohan Mundhra's "Shoot On Sight" based on the London tube-station bombing was shot on actual location.

"Getting permission was tough. The British authorities were very apprehensive because they had read my script. The UK Film Council had to invervene after we protested about artistic muzzling, " Mundhra told.

Such pleas, however, did not work with D'Silva's terror drama. Not any more. The shooting had to be shifted out of London.

Since a major chunk of the terrorists' scenes featuring Saif Ali Khan, Kareena Kapoor, Vivek Oberoi and Om Puri were situated in a tube station, the unit had no option but to shift base to Philadelphia, where permission was not only obtained to shoot in a tube station but an entire train was hired for shooting during off hours.

Confirming this shift of venue Om Puri said: "We were supposed to shoot the film in London but were denied permission to shoot at a tube station.

Now we're shooting in Philadelphia. The paradigms of terrorism and films on the theme have certainly shifted first after 9/11 and now even more so after what has happened in Mumbai."

Even Kabir Khan's next film, which is titled "New York", is on terrorism and was shot in Philadelphia.

John Abraham, who plays lead in the film, says the film was shot in Philadelphia because the topography is similar. "A lot of films located in New York are actually shot in Philadelphia, " said John.

"New York" also stars Katrina Kaif and Neil Nitin Mukesh.

After the Mumbai attacks, terrorism as a theme has found prominence in Hindi films and several filmmakers are attempting to exploit it.

Not only that. It looks like one of Bollywood's beloved villains - the terrorist - is being played by all and sundry.

But Om Puri feels the terrorist shouldn't be Bollywood's favourite villain. "We can't make provocative films on terrorism any more where we show terrorists as snarling villains, " he said.

Om thinks even Neeraj Pandey's much-acclaimed "A Wednesday" featuring Naseeruddin Shah as a terrorist mastermind was provocative.

"Imagine what they'd make of 'A Wednesday' across the border! Now I think the time has come to soften the edges while portraying the terrorist.

In Renzil's film, though I play a terror mastermind I'm not shown as an insane irrational madman. To understand why terror attacks happen we need to understand the terrorists' mind.

My character in Renzil's film is an endeavour in that direction, " said Om Puri.