Children are being constantly bombarded by advertising and promotion of electronics, games consoles, tablets, phones, clothes and designer wear, a new report warns.

Covert advertising propagated by vloggers on YouTube is contributing to the "commercialisation of childhood", the Mothers' Union says today in its latest Bye Buy Childhood report.

"When you go on YouTube you get the little ads pop up in the bottom of a window of a clip or something that you watch. It's subliminal I think at this stage and at an age where they can be very easily led to think that actually this is okay," one parent told researchers. "Well I personally don't think it's ok."

The report is the latest in the Mothers' Union Bye Buy Childhood campaign, launched in 2010 to highlight the charity's growing concerns that childhood has become a marketing opportunity and that children are being targeted by and exposed to inappropriate sexualised media and marketing.

Yet in spite of action taken by Government and Mothers' Union since then, the latest report say there is evidence that advertising and marketing are still the backdrop to the lives of children and young people.

In online surveys for the report, four in five parents were concerned about the commercialisation of childhood, and just half of parents felt equipped to manage the influence of advertising and the commercial world on their family.

The number of parents who feel they have little or no control over watch their children see on social network sites has increased by nearly half, from 24 per cent to 35 per cent of parents.

Four in five adults said that being exposed to the media, such as advertising, films, television and the internet, encouraged their child to ask them to purchase things that they saw advertised, leading to "pester power".

Parents were worried in particular about a lack of control over their children's use of mobile phones.

After the first report, Reg Bailey, chief executive of Mothers' Union, did an independent inquiry which led to the groundbreaking report Letting Children Be Children, and the introduction of new guidelines on on-street advertising, the strengthening of online protection and the creation of the ParentPort online complaints service.

Yet while most of his recommendations were implemented, under a third of parents today believe advertising that can be seen by children is well regulated, a decrease of nine percentage points since 2010. More than two out of three parents fear their children are being harmed by the advertising.

The report calls for the Government to strengthen the wording in the regulation of marketing and selling, to make it harder to comply with the letter of the law, while avoiding its spirit. The report also calls for stiffer penalties.