Aid workers are being targeted throughout Europe as countries including the UK use laws aimed at traffickers and smugglers to discourage humanitarian activity, a study claims.

A six-month investigation by the London-based Institute of Race Relations documented the prosecutions of 45 individual “humanitarian actors” under anti-smuggling or immigration laws in 26 separate actions over the past two years. Examples include a 25-year-old British volunteer with a refugee support group, who last January sought to bring an Albanian mother and two children to the UK in the boot of her car so they could join their husband and father.

She was sentenced in March to 14 months in jail, although the sentence was suspended to take into account her “misguided humanitarianism”. UK law does not distinguish between humanitarian and commercial motives in such prosecutions, but does take such factors into account in sentencing.

In Switzerland, a 43-year-old woman known to refugees as Mother Teresa for her work in providing food for those stranded on the Italian side of the border, was sentenced in September to a fine and a suspended 80-day jail term for helping unaccompanied children into the country.

In France, British volunteers helping refugees in Calais have frequently been harassed by the authorities. In October 2015, former British soldier Rob Lawrie was arrested at the border for hiding a four-year-old Afghan child in his van in response to her father’s pleas to take her to relatives in Leeds. Lawrie, from West Yorkshire, avoided jail after a French court found him guilty of the lesser charge of endangerment rather than assisting illegal entry.

And in March this year three French and British volunteers with charity Roya Citoyenne were arrested for distributing food to migrants.

The 68-page IRR report chronicles a culture of criminalisation in which volunteers for charities and aid groups, attempting to fill the gaps in state provision, are targeted for providing food, shelter and clean water to migrants in informal encampments or on streets.

The EU’s border force, Frontex, has accused aid groups including Médecins Sans Frontières of co-operating with migrant traffickers in the Mediterranean. The report criticises senior Frontex officials for “attempts to bully and delegitimise” NGO search and rescue missions in the Mediterranean by accusing aid groups of working with smugglers and encouraging trafficking.

The IRR’s vice-chair, Frances Webber, said: “Across the continent, criminal laws designed to target organised smuggling gangs and profiteers are distorted and stretched to fit an anti-refugee, anti-humanitarian agenda, and in the process criminalise decency itself.”

This week the IRR will write to the European commission urging it to reassert support for humanitarian values and provide a mandatory exemption from criminalisation for humanitarian groups. The letter warns that the failure to protect aid groups, refugee charities and humanitarian organisations represents a “gulf between law and morality” in the policies of EU member states.

The letter, addressed to the EC’s migration commissioner, states that national authorities are being allowed to “harass, impede and prosecute individuals attempting to help some of the most vulnerable people in European society”.

The group says such criticism has emboldened far-right activists behind the high-profile sea campaign to disrupt vessels attempting to assist refugees in the Mediterranean. A range of Islamophobic anti-immigration groups, along with “alt-light” commentators such as Breitbart News and Junge Freiheit in Germany, joined the campaign.

Austrian interior minister Wolfgang Sobotka has called for legal “punishments” for sea rescuers, and German interior minister Thomas de Maizière has said NGO rescue boats concealed their positions from coastguards but switched on their lights to help refugee boats, claims denied by the NGOs.

IRR director Liz Fekete said: “Those who act in solidarity with refugees and migrants are considered by the far right as self-hating westerners and race traitors. There can be no doubt that the threat of prosecution hanging over search and rescue NGOs and repeated verbal denunciations by European politicians have amplified the far right’s message.”

Activists from French far-right group Ligue du Midi recently ransacked the offices of a group in Montpelier that works with child migrants.