Police officers stand guard at a police cordon next to Buckingham Palace following an incident where a man armed with a knife was arrested outside the palace following a disturbance in London on August 26, 2017. (AFP PHOTO/ CHRIS J RATCLIFFE)

LONDON, Aug. 26 (Xinhua) -- British police on Saturday opened a counterterrorism investigation after three officers were injured arresting a man with a 1.2-meter-long sword outside London's Buckingham Palace late Friday.

Counterterror police are questioning the 26-year-old suspect, who drove a car in front of a police van in a restricted area near Queen Elizabeth's official residence, police said in a statement.

The man reached for the sword after the unarmed officers approached the car and challenged him, police said, adding that the man repeatedly shouted "Allahu Akbar," meaning in Arabic "God is great."

The officers sustained slight cuts in a struggle to detain the man, who took the sword from the front passenger foot-well of his car, the police said.

Police said two of the officers were taken to a hospital for treatment and were later discharged. No members of the public at the scene are believed to have had any interaction with the arrested man.

The suspect was taken to a London hospital for treatment of minor injuries, police said, and he was being questioned at a central London police station.

It is too early to say what the man was planning to do, said Commander Dean Haydon, head of the Metropolitan Counter Terrorism Command.

No members of the British royal family were in Buckingham Palace at the time of Friday's incident, a palace spokeswoman said.

The incident came as police across Europe are on high alert following a spate of terrorist attacks this year. In the Britain alone, three attacks claimed the lives of dozens of people, while police in Spain are probing a suspected terrorist network after twin assaults in the northeastern region of the country earlier this month.