A police officer patrols outside Leytonstone Underground station in east London, Britain December 6, 2015. A man wielding a knife slashed a man in the east London metro station on Saturday, reportedly screaming "this is for Syria," before police used a stun gun to subdue him in what they described as a terrorist incident. [Photo/Agencies]

LONDON - British detectives have charged a man with attempted murder after a knife attack at an east London metro station on Saturday night which was described by police as a terrorist incident.

Police said 29-year-old Muhaydin Mire of east London would appear at Westminster Magistrates' Court later on Monday.

One man, 56, suffered serious but not life-threatening injuries in the attack at Leytonstone underground station, about six miles (10 km) east of central London, while a second person suffered minor injuries.

Eyewitnesses said the attacker had reportedly shouted out "This is for Syria".

Britain is on its second-highest security alert level of "severe", meaning a militant attack is considered highly likely, though not imminent, mainly because of the threat posed by Islamic State militants in Syria and Iraq.

Last week, British war planes joined air strikes for the first time against IS fighters in Syria.

Some lawmakers have warned that the decision would make Britain a target for reprisal attacks, but Prime Minister David Cameron said IS had already planned to target Britain. The authorities say British security forces have thwarted seven terrorism plots in the past year.

After the multiple roving attacks by militants in Paris last month which left 130 people dead, London police said they had boosted the number of armed officers able to respond to incidents.

Deputy Chief Constable Adrian Hanstock from the British Transport Police said the number of firearms teams had doubled in the last year and they had boosted the number of officers and patrols across the London underground network in response to Saturday's stabbing.

"We work very closely with all our intelligence partners and if we do have any indication there is likely to be something significant we intervene," he told BBC radio.