Four people were rushed to hospital after carbon monoxide levels 'high enough to kill' were detected on their Broads cruiser.

Emergency services were called to Somerleyton, near Lowestoft, at around 7pm on Saturday after all six passengers onboard suddenly started to feel unwell.

The passengers, having recently departed from Somerleyton, turned back and called an ambulance for assistance.

Ambulance crews attended and immediately contacted HM Coastguard Lowestoft and Southwold along with the Suffolk Fire service.

David Burwood, coastguard rescue officer, said: 'At first carbon monoxide levels were recorded at 25 parts per million, which is higher than normal. 'This then rose to 240 parts per million.

'To be blunt that's high enough to kill somebody.'

The rescue officer explained a cordon was put in place around the boat for the safety of those attending.

Mr Burwood added: 'Four people were taken off to hospital while the other two felt ok to stay with us.

'And once the area was deemed safe we were stood down.'

In 2016 Alan Frost, 64, and his partner Tina Wilkins, 51, died from carbon monoxide poisoning on a boat moored near Wroxham.

Mr Burwood said this is the first carbon monoxide incident the coastguard had responded to this year and highlighted the importance of working carbon monoxide detectors onboard boats.

He said: 'The message from us and the fire service is very much the same.

'Make sure you have a carbon monoxide alarm on your boat, if not you are putting your life at risk – it is the silent killer.

'The symptoms of carbon monoxide poisoning are very similar to food poisoning; you feel sick, light-headed and dizzy.

'The people on the boat initially thought they had food poisoning from soup they had eaten earlier but thought it was strange to all have it at the same time.'

The rescue officer also took the opportunity to highlight what to do if in trouble on The Broads.

Mr Burwood said: 'Our normal message if to call 999 and request the Coastguard. However they did the right thing and called for help when they knew they were in trouble.'