A fire on the London Underground transport system on Friday left several people injured in what police were treating as a terrorist incident, the Metropolitan Police reported.

In a statement, the Met confirmed that they were attending the scene at Parsons Green tube station, located in southwest London, and that surrounding areas had been cordoned off.

"The Met’s Counter Terrorism Command are investigating after the incident at #ParsonsGreen tube station is declared a terrorist incident," a statement on the force's Twitter account said.

Downing Street announced that Prime Minister Theresa May would be presiding a Cobra emergency committee meeting in the afternoon to discuss the incident.

Images by an epa photographer on the ground showed a woman with a bandaged face being escorted away from the scene by emergency services.

Several UK media outlets reported that the incident had involved a small explosion and several passengers had sustained burns from the conflagration.

The BBC showed aerial images of a train being evacuated in an orderly fashion, with passengers walking off the lead wagon through a door at the front.

The London Fire Brigade said around 50 firefighters and specialist officers were on the scene, alongside several fire trucks and two rescue units.

Speaking to Sky News, British foreign secretary Boris Johnson said there was not yet much information but that police were on the case and would be keeping the public informed.

"Everybody should keep calm and go about their lives in as normal a way as they possibly can," he said, adding that "it really is important not to speculate at the moment."