Ireland’s Taoiseach (prime minister) Leo Varadkar was branded “a disgrace” during a heated debate over medicinal cannabis in the lower house of parliament.

Opposition TD Gino Kenny of the People Before Profit party grilled the country’s most senior politician about the delay in rolling out a medical marijuana scheme, which the government agreed to back in 2016. Varadkar said the delays were due to the difficulty it has had in finding a suitable supplier that can produce cannabis of a high enough standard for medical use.

But then the Taoiseach pulled out a poster from a People Before Profit meeting held in County Mayo in March 2017. Varadkar said a constituent had sent it to him. The poster contained numerous messages, including the slogan “cannabis kills cancer”.

The Taoiseach then accused People Before Profit of championing a false and dangerous claim that will damage people’s health and cost lives. Kenny reacted with fury, as all props – including posters – are banned in the Dáil, while another opposition party, Sinn Féin, also challenged him about using the poster.

Kenny called him “a disgrace” and said it is the lowest thing he has ever seen in parliament. He later took to Twitter to vent his frustration: “Today at promised legislation I raised the legitimate concerns on the delay around the proposed Cannabis Access Programme. It’s now two years since it was first mooted. Instead of answering the concerns Leo Varadkar chose to try and discredit PBP on the substantial issue.”

Kenny supporters said red tape and blockages suit the government’s agenda, claiming the delay would drag on until after the next general election in 2021. The Irish health minister can hand out a licence for medicinal cannabis use if a specialist doctor applies on behalf of a patient, but protestors say the process is so strict that it makes it impossible for anyone to source marijuana.

For instance, Vera Twomey has recalled the journeys she has to make to The Netherlands to buy cannabis for eight-year-old daughter Ava, who suffers from severe epilepsy.

Irish officials visited Denmark this month to learn about the country’s success in rolling out a regulated medicinal marijuana trade. It reported that it has made significant progress in its bid to help Irish patients gain access to the drug, but opposition politicians remain highly critical of the delays.

Fianna Fáil leader Micheál Martin said the Dáil has been “extremely patient” regarding the delays, but warned they cannot go on, while Kenny continues to lambast the “effective embargo” imposed by Varadkar’s party.