British consumers are more aware of the issue of silent phone calls, and this knowledge may be behind an increase in the level of complaints about it, a watchdog report says.

The number of complaints to the telecommunications regulator has settled at between 1,000 and 1,300 per month in the UK after a spike from 590 to 1,924 in the first two months of the year, Ofcom said.

The regulator explained that a consultation it ran last year put the issue in the public eye and new rules came into force in February, both of which may have meant consumers are more aware of abandoned calls and know how to complain.

Ofcom research suggests fewer people have been getting the troublesome phone calls over the last couple of years - with the level at 24 percent this year for UK adults who have landlines, down from 30 percent for 2009. Firms whose calling procedures break the rules face a maximum fine of €2.3 million as of last September.

The report said most silent calls have no "malicious or mischievous intent" and are created by the systems that call centres use to automate dialling numbers. But it said: "Despite the likely cause of their origin, these calls still understandably cause annoyance, inconvenience and anxiety."