Imran Khan reports on Yemeni civilians left homeless after a military air raid on al-Qaeda fighters.

Al-Qaeda's Yemen-based wing has threatened more small-scale attacks against the US to inflict economic damage, particularly to the aviation industry.

The group, Al-Qaeda in the Arabian Peninsula (AQAP), said it had cost just $4,200 to mail two parcel bombs from Yemen to the US last month. The bombs were intercepted in Britain and Dubai, sparking a worldwide security alert.

Alerted to the late October bomb plot by Saudi intelligence, security officials chased the packages across five countries, trying over the next two days to prevent an explosion that could have come at any moment.

AQAP said it is part of a new strategy to replace spectacular attacks in favour of smaller attacks to hit the US economy, according to a special edition of the online Inspire magazine, released on pro-al Qaeda websites and made available by both IntelCenter and the Site Intelligence Group.

"It is such a good bargain for us to spread fear amongst the enemy and keep him on his toes in exchange of a few months of work and a few thousand bucks," the statement said.

"We are laying out for our enemies our plan in advance because as we stated earlier our objective is not maximum kill but to cause [damage] in the aviation industry, an industry that is so vital for trade and transportation between the US and Europe".

AQAP said: "Two Nokia mobiles, $150 each, two HP printers, $300 each, plus shipping, transportation and other miscellaneous expenses add up to a total bill of $4,200. We will continue with similar operations and we do not mind at all in this stage if they are intercepted.

"To bring down America we need not strike big."

Soon after the discovery of the explosive printers, AQAP had also claimed responsibility for the crash of a UPS cargo jet in Dubai in September, but US officials have said that there were no indications that the parcel delivery company's aircraft had been brought down by an attack.

The US stepped up airline passenger security after a Nigerian man tried to detonate explosives hidden in his underwear on a flight from Amsterdam to Detroit in December last year.