A British court has convicted a husband and wife of planning a major terror attack to mark the 10th anniversary of the London suicide bombings this year.

Mohammed Rehman, 25, used the Twitter name 'Silent Bomber' and asked users whether he should bomb a shopping centre or the London Underground train network.

Rehman used as his profile picture an image of the so-called Islamic State group militant known as 'Jihadi John', believed killed earlier this year, and was said by prosecutors to have had a "keen interest" in IS.

He was arrested in May after posting a tweet saying: "Westfield shopping centre or London underground? Any advice would be greatly appreciated."

That was accompanied by a link to an Al-Qaeda press release about the July 2005 bombings in which four suicide bombers targeted London's transport system. Fifty-two people were killed.

The couple were accused of planning their attack around May 28.

Rehman and his wife Sana Ahmed Khan were found guilty by a jury at the Old Bailey in London, England's central criminal court.

Police also seized more than 10 kilogrammes (22 pounds) of urea nitrate, which can be used to manufacture a large bomb, from their house.

"The manufacture of a detonator would have taken no more than a couple of days and could have been done by him much quicker if he chose to," prosecutor Tony Badenoch told the court.

While Rehman was responsible for creating the bomb, his wife funded his exploits and bought the chemicals, the Crown Prosecution Service (CPS) said.

The couple will be sentenced tomorrow or Thursday, following mitigation hearings.