Image Courtesy: Metropolitan Police Twitter account

LONDON: British police investigating Friday's sword attack outside Buckingham Palace in London released a suspect from custody on Wednesday, but another man is still being questioned.

"A 30-year-old man who was arrested in west London on Sunday, 27 August by detectives investigating a terrorist incident near Buckingham Palace has been released from police custody with no further action," a police statement said.

A 26-year-old man from Luton, north of London, was arrested at the scene on suspicion of grievous bodily harm and assault on police, and the counter-terrorism department has until September 1 to question him.

The suspect reached for a four-foot (1.2-metre) sword after being challenged by unarmed police officers he deliberately drove at outside the royal palace, authorities say.

Police said the man repeatedly yelled and was incapacitated with CS gas.

"We believe the man was acting alone and we are not looking for other suspects at this stage," said Dean Haydon, the head of Counter Terrorism Command.

"While we cannot speculate on what the man was intending to do ? this will be determined during the course of the investigation ? it is only right that we investigate this as a terrorist incident at this time."

In Britain, 35 people have been killed in three extremist attacks in London and Manchester since March.