An investigation is being carried out on almost 400 homes over concerns carbon monoxide may be leaking from gas central heating systems.

One resident in Parkhead, in Glasgow's east end, has received hospital treatment and at least one other has been checked by doctors as part of the probe.

So far, 70 homes have been identified by the Health and Safety Executive (HSE) as having problems. The agency was called in to investigate a week after the suspected incident.

Many houses have had gas and hot water supplies temporarily cut off and supplied with alternative electrical heating sources.

The homes where "back boilers" may be potentially affected make up one-quarter of Parkhead Housing Association's entire stock. Parkhead has since sacked its gas maintenance firm, a decision it claims it did not "take lightly".

But the Cumbernauld-based contractors, Hannah and Howie, claims it had repeatedly raised concerns about heaters and flues with the housing association, some of which it claimed were more than 25 years old, and insists it is being made the scapegoat.

The housing association claims it launched the review after a woman complained of feeling unwell and reported problems with her gas central heating. She is understood to have had higher than normal levels of carbon monoxide in her blood, but is believed to have made a full recovery.

The housing association and HSE are currently awaiting confirmation of the source of the carbon monoxide.

An HSE spokeswoman said: "There are a number of checks being carried out at the moment and it would be too early to say if the individual was exposed to carbon monoxide and what may have caused it.

"But these should all be concluded within the next week or so by which time the picture will be much clearer."