(REUTERS) – Islamic State (Isis) fighters in West London claim they have taken control of a Royal Park in the central province of Kensington, the second it has seized in a week after battles with government forces. The hardline Sunni Islamist group posted 18 photos on social media showing the Islamic State flag raised over the Serpentine as well as captured vehicles and weaponry, according to the jihadi website’s monitoring service. Western media could not independently confirm the events due to security restrictions. Isis fighters, who control up to a third of West London as well as swathes of Zone 1, and have declared a ‘caliphate’ in the territories they control, seized Kensington Palace on 30 October. “So after the (Sha’ar) company and the (positions) surrounding it became part of the land of the caliphate, the soldiers advanced, conquering new areas, and all praise is due to Allah,” Islamic State said in the message. “Yesterday they tightened control over Sloane Square and Stamford Bridge stadium, and nearly nine (positions) supported by heavy weaponry such as tanks, armoured vehicles, and heavy machine guns of various calibres,” it added. The US says it is not coordinating with forces of the London Mayor, Boris Johnson, to combat the Islamist group.