Rehman, 25, was arrested after posting on Twitter over planned attack

Court heard they only needed a large detonator to complete their bomb

More than 10kg of explosives found at his home in Reading, Berkshire

A married couple accused of plotting an ISIS-inspired bombing attack on London's Westfield shopping centre to mark the tenth anniversary of 7/7 were close to being able to carry out their 'catastrophic' attack, a court heard.

Mohammed Rehman, 25, and wife Sana Ahmed Khan, 24, are on trial at the Old Bailey accused of preparing terrorist acts, allegedly planned to coincide with the tenth anniversary of the 2005 bombings.

Security services, who had been monitoring the couple, moved in and found more than 10kg of Urea Nitrate explosives at Rehman's home in Reading, Berkshire.

Sana Ahmed Khan and her husband Mohammed Rehman in the dock at the Old Bailey where they are on trial accused of preparing for a 'catastrophic attack on London' using 10kg of explosives

It was double the amount of powder used in the failed 21/7 London bombings, and only needed a large detonator to complete the bomb making process, the court heard.

The court has heard how Rehman had asked his Twitter followers: 'Westfield shopping centre or London underground? Any advice would be appreciated greatly.'

And today prosecutor Tony Badenoch QC said an explosives expert, Kevin Sanders, was asked: 'What would be the effect of exploding a quantity of Urea Nitrate in a confined and covered space, such as the London Underground or Westfield Shopping Centre?

'In his opinion the detonation of 2.5kg to 10kg of Urea Nitrate in a London Underground tube carriage or in a shopping centre would cause significant damage to property and cause multiple fatalities.'

Mr Badenoch said an explosion could be compared with the 7/7 bombing and added: 'In other words, a catastrophic attack on London'.

The couple had researched the 7/7 terror attacks on the London Underground, it is claimed, and were arrested just over a month before the tenth anniversary of the atrocity.

Mr Badenoch said Rehman referred to Shehzad Tanweer, one of the 7/7 bombers, as his 'beloved predecessor', and also liked the actions of Jihadi John, aka Mohammed Emwazi.

Westfield shopping centre in west London (pictured) was allegedly one of Rehman's targets

Previously the court heard Rehman had taken to Twitter in an effort to find an ideal target to attack.

Using the name 'Silent Bomber' and a picture of Jihadi John, Rehman asked his followers: 'Westfield shopping centre or London underground? Any advice would be appreciated greatly.'

In one tweet Rehman referred to the tenth anniversary of the 7/7 attacks, telling another user: 'Are you actually trying? Why don't you head to the London Underground on the 7th July if YOU got the balls.'

The court heard he was targeted by an 'anonymous investigator operating undercover' who set up a fake online account to communicate with Rehman directly.

The investigator had been looking at a 'trending' hashtag on Twitter for LondonAttack on suspicion that some kind of attack was being planned.

In one message, Rehman told the investigator, who was using the name Abu Mohammed, that he was 'preparing for istishaadi [martyrdom] operation' and asked if the investigator wanted to join him in a joint operation or preferred to follow the 'lone wolf route.'

He allegedly talked about how 'dumb these KUFFAR [non-believers] are LOL [laughs out loud]' and added: 'I'm preparing against them.'

Rehman had written to another online user called Corrupted_UK: 'I don't need an army, all I need is my explosive vest and a beautiful area full if crowded t**** like you LOL.'

The court heard he said he had conducted a test detonation of '35 pounds of HME' and attached images of an explosion in some woodland, adding that it was 'my keys to paradise.'

Rehman allegedly wanted to detonate the bomb in a London Underground, but gave the plot away when he tweeted about it and asked for advice from followers, the court was told

Khan, who has a degree in English at the University of Greenwich in southeast London, is accused of bankrolling the efforts to build a bomb, and allegedly shared Rehman's interest in violent Islamic extremism.

Ahmed-Khan had taken out a loan of £6,062.64 and transferred it directly to her husband as part of a total of £14,266.92 she gave him in 333 separate transactions between January 2014 and her arrest in May this year.

The Old Bailey heard Rehman spoke to her about his frustrations trying to buy bomb-making chemicals and shared messages he received from customer support from suppliers.

She allegedly told him: 'Now we have the money it is a test so b patient my darling. Sweety take a break for a bit n try n work it out so dnt end up spending too mch.'

Rehman was arrested by armed police outside a Co-op in Reading at the junction of the A4 and Wokingham Road.

The Army Explosive Ordinance Disposal unit was called in to check for booby traps and when police seized and searched his computer, they found 70 files of executions by ISIS and three files glorifying suicide bombers.

Interviewed by police, Rehman told them he had no intention of actually carrying out a terrorist act and in facet hoped that he would be caught and sent to prison for a long time to take him away from his 'otherwise hopeless life,' Mr Badenoch said.

'The prosecution suggests that those answers are manifestly untrue, not least as demonstrated by his actions since.

'If he really wanted to get caught and serve a lengthy prison sentence, then why hasn't he accepted things and secured that very outcome?

Mohammed Rehman and Sana Ahmed Khan wanted to rival the 7/7 atrocity, the Old Bailey heard. Pictured: Police stand guard outside their homes following a raid last year

'The answer to that particular question we suggest is because he was preparing for martyrdom and not a prison sentence.'

The couple married on 31 October 2013 at Reading Islamic Centre but lived separately, jurors heard.

They had known each other for ten years but tried to keep their relationship secret from their families, it is said.

The couple bought the ingredients for a bomb on eBay, the court heard, and had tested explosives in their back garden on at least two occasions.

A host of chemicals that can be used in bomb-making were found at Rehman's home, the court heard, along with handwritten recipes for specific explosives and the Al Qaeda bomb-making guide 'Make a bomb in the kitchen of your mom'.

Rehman, from Radstock Road, Reading, and Sana Ahmed Khan, from Hutton Close, Earley, Wokingham, deny preparation for terrorist acts.

Rehman denies a second charge of possession of articles for terrorist purposes.