The Salvation Army has hit back over criticisms regarding its role in providing unpaid work placements for people on benefits.

Campaigners from the Boycott Workfare organisation picketed the Salvation Army's international headquarters in London at the weekend. They argued that the charity's involvement made it complicit in the much-criticised benefit sanctions regime, which sees people lose benefits for offences such as failing to turn up for an interview on time or refusing to take work when it is offered.

Around 540 charities have signed up to the "Keep Volunteering Voluntary" pledge, which says:  "Workfare schemes force unemployed people to carry out unpaid work or face benefit sanctions that can cause hardship and destitution. We believe in keeping volunteering voluntary and will not participate in government workfare schemes."

Spokeswoman Joanna Long said: "Charities like the Salvation Army are meant to help people, not make them poorer, but workfare schemes do just the opposite. People are forced to work without pay or face destitution. Sanctions are driving food poverty in the UK. So it's a mystery how Salvation Army – which also runs foodbanks – can justify its involvement in the sanctions regime."

However, a Salvation Army spokesperson said: "In these tough economic times unemployed people need more help than ever to get and stay in work. We have seen first-hand the positive benefits people gain from being in work, volunteering or taking part in a work-experience placement – becoming part of a community where you are building your confidence, job skills, and discovering new things about yourself."

Some local Salvation Army centres have accepted people on "mandatory work activity" short term placements. However, the spokesperson said: "We feel that a 26-week work experience placement is too long and would not be beneficial. If someone has not found employment within two years, the lack of work experience is clearly not their only barrier to employment. Our concern is that the underlying issues need to be dealt with holistically and work experience is a part of the support needed. As such, we are not taking part in the Community Work Placement programme."

The spokesperson said that benefit sanctions were "getting in the way" of efforts to find people jobs and homes, adding: "We submitted evidence to the Work and Pensions Select Committee Inquiry into Benefit Sanctions. We agreed publicly with their conclusion that a review of the current system of benefit sanctions is needed. We call upon the next government to pick up that recommendation."

However, Joanna Long told Christian Today: "You don't need an enquiry to say that sick and disabled people shouldn't have their benefits taken away."

She said that mandatory work schemes were wrong in principle as they relied on benefit sanctions if people failed to comply: "It is never acceptable to punish people by taking away their ability to eat."