A British couple were convicted on Tuesday of plotting an attack in London after the husband sent out tweets asking for advice on which targets he should hit, alerting police to a stockpile of chemicals at their home.

Mohammed Rehman, 25, and Sana Ahmed Khan, 24, were found guilty by a jury at the Central Criminal Court of engaging in the preparation of terrorist acts, with a view to hitting either a large shopping center in the capital or the London underground network.

"Westfield shopping center or London underground? Any advice would be appreciated greatly," Rehman said on Twitter, under the name "Silent Bomber".

The couple, who denied the charges, are to be sentenced at a later date.

The British prosecutor said on Tuesday the two Britons had carried out detailed research into militant attacks, including searching the Internet for videos related to the London transport bombings which killed 52 people a decade ago.

Those attacks were carried out on July 7, 2005 when four young British Muslims traveled from northern England to the capital to detonate homemade bombs hidden in rucksacks on three underground trains and a bus during the morning rush-hour.

British media reports said Rehman and Ahmed Khan had planned to carry out an attack to coincide with the 10-year anniversary of those earlier bombings.

Rehman, who was also found guilty of possessing an article for terrorist purposes, had carried out test bombs in his garden which he filmed and sent to his wife, and she had also helped to purchase the chemicals, the prosecutor said.

"The pair had been very close to carrying out an attack, all they required was to purchase the chemicals to make a detonator," said Susan Hemming, Head of Counter Terrorism Division at the Crown Prosecution Service.

She added that the couple had already acquired 10 kg (22 pounds) of Urea Nitrate. "There is little doubt that, had Rehman and Ahmed Khan not been stopped when they were, they would have attempted to carry out an act of terrorism in London."

Britain is on its second highest alert level of "severe", meaning an attack by militants is considered highly likely. The designation remained the same after the Nov. 13 Islamist attacks in Paris that killed 130 people.