Four young Islamic terrorists allegedly planned to stab Queen Elizabeth II, 88, to death at the Royal British Legion Festival on Saturday, reports The Sun.

Since Thursday evening, London's armed Metropolitan Police Service had raided homes in West London and Buckinghamshire, arresting four suspects between the ages of 19 and 27 on suspicion of commissioning, preparing or instigating acts of terrorism under the Terrorism Act 2000, according to The Sun.

Computers and documents were taken from the suspects' homes for examination. In a statement Scotland Yard said: "These arrests and searches are part of an ongoing investigation into Islamist related terrorism."

According to the Sun, the Queen was informed of the assassination plot but it did not stop her from attending weekend events, including the annual Remembrance Day ceremonies at the Cenotaph in Whitehall, London, on Sunday.

Queen Elizabeth II has not released a public statement about the allegations.

The arrests and searches follow Britain's October 8 and September 25 arrests of 13 men for alleged terrorism offenses.

In August, Britain received intelligence of possible terrorist attacks and increased its terror threat to "severe," the second-highest level.

Britain experienced a total of 69 terror-related arrests the first six months of this year, according to London's Metropolitan Police Service.

The weekend arrests are evidence of the growing threat facing Britain, the U.S. and their allies as they battle ISIS fighters in the Middle East.

More terrorist attacks are expected following the U.S.-led coalition of 23 air strikes in Syria and 18 in Iraq conducted against the Islamic State since Friday, reports Business Insider. Among the targets hit in Syria were an ISIS vehicle, an ISIS-occupied ammunition storage building, an ISIS command and control building, and seven ISIS fighting positions.

The Obama administration announced on Friday that 1,500 more soldiers have been deployed to train Iraqi and Kurdish forces. The deployment will nearly double the number of American troops in Iraq.