British Gas may be making unsolicited phone calls to more than four million homes every year, a survey found yesterday.
The energy giant, which made profits of more than £600million last year, was among the biggest users of cold calling, according to the research.
The marketing calls are often regarded as a nuisance or even sinister.
There has been particular concern over ‘silent’ calls, when householders pick up the phone but no voice speaks to them.
The scale of marketing calls was estimated following a survey carried out in 20,000 homes where an answering unit was fitted to record the number of incoming calls.
British Gas was among the most prolific callers, the results showed.
It made 7,000 cold calls to 900 homes over the course of a year, almost eight calls to each household.
If unsolicited calls from British Gas are made on the same scale nationwide, researchers calculated, it is likely to have made calls to 4.1million homes.
Its involvement in the unpopular marketing approach threatens fresh embarrassment for the firm at a time when its high profit levels have been attracting criticism.
Figures published last week showed profits of £606million, swelled by increased energy use during the first months of the cold winter, and a 6 per cent price increase in November.