The government is increasingly using value-laden and pejorative language when discussing benefits and welfare, a Guardian analysis has found, something poverty charities warn is likely to increase the stigmatisation of poor people.

The findings show that the work and pensions secretary, Iain Duncan Smith, has spoken of a mass culture of welfare dependency in every speech on benefits he has made in the past 12 months.

The analysis comes after complaints that the government is using exceptional cases such as that of Mick Philpott, the unemployed man jailed this week for the manslaughter of six children, to justify its programme of changes to the benefits system.

An examination of Department for Work and Pensions (DWP) speeches and press notices connected to benefits in the year to April 1 shows a significantly increased use of terms such as "dependency", "entrenched" and "addiction", when compared with the end of the Labour government.

Fraud, which accounts for less than 1% of the overall benefits bill, was mentioned 85 times in the press releases, while it was not used at all in the final year of Labour, which was itself accused of sometimes using intemperate language on the issue.

In the 25 speeches by DWP ministers on welfare over the year, "dependency" was mentioned 38 times, while "addiction" occurred 41 times and "entrenched" on 15 occasions. A comparison of 25 speeches on the subject by Labour ministers saw the words used, respectively, seven times, not at all, and once.

Some charities warn that such language fuels a distorted portrayal of benefits in parts of the media, which in turn perpetuates widespread myths about the welfare system. A YouGov poll for the TUC last year found that, on average, people think 41% of the welfare budget supports the unemployed – the true amount is 3% – and believe the fraud rate is 27%, as against the government's estimate of 0.7%.

The DWP's language was unhelpful and appeared to be getting worse, according to Helen Barnard, policy manager at the Joseph Rowntree Foundation. She said: "It misrepresents what poverty is about. It sets up this idea that there are poor people and people on benefits and then everybody else, and never the twain shall meet. When you look at the research, it's very much the opposite. The majority of people in the UK will experience poverty at least once in their lifetime. The idea that poverty is experienced by another group that is fundamentally different to everyone else is completely wrong."

Tim Nichols from the Child Poverty Action Group said his organisation believed government rhetoric on the issue was changing, having a real effect on those claiming benefits.

He said: "It's without doubt got worse. It is very much linked to the fact they've got a major programme of cuts to social security under way, and are seeking a narrative to justify this. It's becoming increasingly hard for us to find people in poverty or receiving benefits who are happy to speak about their situation in the media. They fear the effect of this stigmatisation if they put themselves in the spotlight – how it might affect them and their children. They really are scared."

Duncan Smith appears to be the most frequent user of value-laden terminology, regularly including terms such as "entrenched and intergenerational worklessness and welfare dependency" in his speeches. Campaigners particularly challenge his regular claim of benefit dependency over generations; arecent study was unable to find any families where three generations had never worked and a only tiny number where this could be the case for two generations.

Analysis of language in the media a similar picture. In the past year, the term "benefit cheat" was used 442 times in national newspapers, an increase of almost two-thirds on the 12 months before the coalition took power.

The DWP said: "We are very clear that it is the welfare system that is failing individuals, not the other way around and our language always reflects that. Currently, people are being trapped on benefits or are missing out on the support they are rightly entitled to. Our reforms will end the benefits trap, and will also make it easier for people to claim the help they need."