Television viewers were exposed to almost 400,000 payday loan adverts last year - a year-on-year increase of 64%, according to Ofcom.

Each adult saw an average of 152 payday loan ads on television last year, while the average child aged between four and 15 saw 70 of the ads during the same time.

The study found that there were 17,000 payday loan ad spots shown on television in 2008, increasing to 243,000 in 2011 and 397,000 last year.

Payday loans accounted for 0.1% of all advertising spots broadcast across all commercial television channels in 2008, compared with 0.7% in 2011 and 1.2% last year.

Children aged four to 15 saw three million payday loan television adverts in 2008, growing to 466 million by 2011 and 596 million last year.

Children's channels accounted for 3% of payday loans "impacts" seen by four to 15-year-olds last year, equivalent to two impacts per child on these channels over the year, Ofcom said.

Last year, more than half (55%) of all payday loans adverts on television were broadcast in the daytime schedule between 9.30am and 4.59pm.

Ofcom said it would continue to monitor trends in television advertising for payday lending to inform its understanding of the area.

The content of advertising is regulated by the Advertising Standards Authority (ASA).

Peter Tutton, head of policy at the debt charity StepChange, said: "As payday lenders continue to invest in attracting new customers, we continue to see the number of people struggling with payday loans increase.

"If the payday loan industry is serious about addressing the harm done to consumers, then it needs to use its resources to tackle the problem of widespread irresponsible lending that is pitching tens of thousands of people into serious financial hardship."

The union Unite called for a 9pm watershed for payday loans adverts.

Unite assistant general secretary Steve Turner said: "This research paints a horrific picture of a generation of children and young people being groomed into a culture of debt by this bombardment of advertising.

"It is not just children being infected by this payday loan culture. Research has shown that people are borrowing £660 a month just to pay for the necessities of life - food, housing and heating.

"The ASA should give a robust lead in introducing a 9pm watershed for these payday loans so that children are not influenced by this insidious onslaught.

"The number of adverts should be curbed as the public are being duped into thinking that getting into debt is an easy option and pain free - quite the contrary."