Evacuated Portsmouth tower block residents are allowed home after reports of a chemical incident

It saw residents living below the 12th floor of Tipton House in Warwick Crescent, Somers Town, evacuated shortly before 4pm.

David Kyffin, who lives on the 11th floor, said firefighters asked him and others to leave their flats because of a ‘suspected ammonia leak’.

But a spokeswoman for Hampshire Fire and Rescue Service later confirmed its crews found ‘nothing’ after probing with specialist equipment.

The service sent three engines from Southsea and Cosham to the scene with an environmental protection unit and a response support vehicle.

South Central Ambulance Service also attended, as well as police – who shut off Warwick Crescent at its junctions with Grosvenor Street.

A spokesman for Portsmouth City Council confirmed residents who were evacuated were allowed to return to their homes at about 7pm.

It is understood some were checked by paramedics at the scene, but it is not yet known whether anyone needed further treatment.

A spokeswoman for South Central Ambulance Service said: ‘We were called at 4.20pm to Warwick Crescent to reports of a chemical incident.

‘We have sent to the scene an ambulance crew, Hazardous Area Response Team and two ambulance officers to assess and treat and potential casualties.’

Ammonia is a colourless gas frequently used in household cleaning products.