Northern Ireland is to have its first-ever party political broadcast by a party campaigning solely for reform of Britain’s drug laws on Thursday night.

The Cannabis Is Safer Than Alcohol party (Cista) has registered 32 candidates for the general election, including four in Northern Ireland, enough to qualify it for a five-minute slot on television there.

The four-and-a-half minute film airs on UTV and focuses on the medicinal qualities of cannabis, which patients say prevents seizures, relieves nausea and eases pain.

“These are qualities which can enhance my daily life and counter some of the effects of the pharmaceuticals which I am prescribed,” says Glenn Donnelly, a Cista candidate and one of the voices in the broadcast.

Cista’s chair, Paul Birch, who made millions from the sale of the social network Bebo and who has invested £100,000 in the party, said the party had decided to focus on the medical uses of cannabis because “we felt like it was the easiest thing to get through”.

Birch said many of Cista’s supporters were long-term users of opiate medicines who were sick of the side-effects of the drugs. “Taking cannabis enables them to have pain relief and have a normal life,” he said.

Cista is calling for a royal commission on drug law reform, of the kind suggested by the home affairs select committee and dismissed by David Cameron, the prime minister, in 2012. “This is a basic human right,” Birch told the Guardian. “Cannabis has medical uses, clearly, and yet the home secretary has stood up in parliament and said it doesn’t.”

Cannabis campaigners welcomed the broadcast. Stuart Harper, a spokesman for Norml UK, which campaigns for the legalisation of cannabis, said: “Norml are tremendously pleased at the newly made party political broadcast. For the first time ever on UK television the honest and impartial view about cannabis will be presented to the nation.”

But some politicians in Northern Ireland were disappointed with the opportunity offered to Cista. The first minister, Peter Robinson, of the rightwing DUP, told the Belfast Telegraph: “It shows how ludicrous electoral law and the role of broadcasters has become when we get cranks being given airtime for that. Why not have Screaming Lord Sutch on the leaders’ debates?”

YouGov polling commissioned by Cista and provided to the Guardian in February showed 44% of voters support the legalisation of cannabis, versus 42% who want it to remain banned

Birch conceded that he did not expect any significant change in policy after the election, but indicated that his strategy was to raise awareness of cannabis law reform through the campaigning opportunities the election will provide.

“We have recruited 32 candidates for the election and we have given them some training to speak in the hustings and try to get through to other candidates,” he said. Of the other candidates, eight are standing in Scotland, one in Wales and the rest in England, including nine in London.

Cista will be no flash in the pan, Birch promised. He said he was already looking forward to future elections to Westminster and the devolved assemblies. “There are some opportunities in Scotland to do things differently around drugs, like they have done on their drink-driving,” he said.

For Birch the campaign to legalise cannabis has personal importance. “I consume both [cannabis and alcohol],” he said. “I probably, as a result of cannabis being illegal throughout my life, have consumed more alcohol than I would have done.”

“It’s not even close between alcohol and cannabis in terms of safety, but the public are told something different,” he said, adding that studies which claim cannabis causes schizophrenia are contradicted by a lack of increase in diagnoses despite a huge rise in use of the drug.

“The facts about the reality of the situation are being buried,” Birch said. “We are looking to try to highlight some of those facts through being a political party.”

The party election broadcast for Cista will be shown at 11.05pm on Thursday on UTV in and will be repeated on the BBC and Channel 4 in Northern Ireland next week.

Cista’s broadcast is not the first from a UK party campaigning solely on the issue of drugs law reform. In 2005 the Legalise Cannabis Alliance contested seven seats in Wales, enough to qualify for a broadcast in the country. The party contested a total of 21 seats across the country, with their best result in Orkney and Shetland, Scotland, where they won 1.8% of the vote.