Officers investigating an alleged arson incident at Highfield House Hotel have appealed for information.
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The hotel houses asylum seekers and has been the scene of protests and counter protests in recent weeks.
Hampshire and Isle of Wight Constabulary said they were called around 2.15am on Sunday (Sept 7) after a flare was reportedly put through an open ground-floor window.
The fire caused by the flare was quickly extinguished and nobody was injured, said the force, who are now enquiring further into the incident.
They want to locate two people seen approaching the hotel and who were then seen “fleeing the scene” along Shaftesbury Avenue.
One was wearing a dark hooded top and had his face covered, and the other had a white hooded top on.
Chief Inspector Chris Douglas said: "Fortunately, this fire was quickly put out, but this was an extremely dangerous act and could have had fatal consequences.
"Our local neighbourhood policing team will be carrying out additional patrols in Portswood in the coming days, and if anyone has any concerns then please do speak to them.
"I want to urge anyone with information, however small you think it may be, to get in touch and share this with us. If you have any CCTV which may have captured the two men either in the moments leading up to or after the incident, then we would ask you to share this with us.
"We are working closely with local authorities as part of this investigation."
You can also contact the independent charity Crimestoppers anonymously on 0800 555 111, or via their anonymous online form at crimestoppers-uk.org.