London, Nov 2 (IANS) Each of the two parcel bombs mailed to US-based synagogues, which were detected on board flights in Britain and Dubai, contained enough explosives to blow up 50 jets, British experts said.

The capability of Al Qaeda’s latest weapons was revealed as British Home Secretary Theresa May confirmed that fanatics in Yemen who hatched the plot were thought to be planning fresh attacks, The Sun reported Tuesday.

Both bombs were sent from Yemen, addressed to Jewish synagogues in Chicago. One was seized on a cargo plane at East Midlands Airport in Britain. The other was found in a FedEx depot in Dubai.

Security officials found 300 grams of the powerful substance pentaerythritol tetranitrate (PETN) in one of the bombs hidden in computer printer cartridges, and 400 grams in the other.

According to experts, just 6 grams of PETN – around 50 times less than was used – would be enough to blast a hole in metal plate twice the thickness of an aircraft’s skin.

‘That amount of PETN could do a whole lot of damage,’ Hans Michels, professor of safety engineering at University College London, was quoted as saying.

‘It could sink the QE2 or destroy a house. It would have blown a hole in the side of the ship and it would have almost certainly gone down. If it had been close to the wall of the aeroplane, it would definitely destroy it. PETN is a very powerful explosive,’ Michels said.

The team at the government’s Fort Halstead research complex in Kent is also trying to work out the planned timing of any blasts, to identify the targets.

A source said: ‘It would appear from the evidence so far that the terrorists wanted the devices to be in the air for as long as possible.’

‘We believe that may be one reason why the packages were addressed to Chicago – because of the length of flight times involved.’

‘Now we are trying to work out whether Al Qaeda wanted the bombs to explode when the aircraft were over the Atlantic or over land. If the planes plunged into the sea, it would have been deduced a terrorist attack – but finding the precise cause would have been almost impossible,’ the source said.

‘Work is ongoing as a result to attempt to figure out how long it would have been before devices would have gone off after take-off.’

Another 26 suspect packages seized in Yemen are still being analysed.

Home Secretary May said in a statement that the terror group behind the ink bomb plot – Al Qaeda in the Arabian Peninsula – had already launched attacks on British diplomats in Yemen, in April this year and last month.

‘We are in a constant battle with the terrorists. They are always looking for another way to try to get around our defences,’ she said.