The Canadian government is investigating reports that Saudi Arabia is using armoured vehicles made in Canada against its own civilians – allegations that have prompted renewed scrutiny over Ottawa’s recent decision to sign off on a billion-dollar arms deal with the kingdom.

Videos and photos posted on social media in recent days allegedly show Riyadh using Canadian equipment in a violent crackdown on minority Shia dissidents in eastern Saudi Arabia. Last week at least five people were killed as security forces flushed out suspected militants in the town of Awamiya.

Several sources told the Canadian newspaper the Globe and Mail that the vehicles being used appeared to be Gurkha RPVs made in Ontario by Terradyne Armoured Vehicles.

Canadian officials said they were deeply concerned by the reports. “We are looking at these claims very seriously … and have immediately launched a review,” Justin Trudeau told reporters.

In 2016, Saudi Arabia ranked among the largest importers of Canada-made military goods, purchasing more than C$142m worth of goods – nearly 20% of all Canadian military exports that year.

The ministry of global affairs said it was concerned over the escalating violence in eastern Saudi Arabia. In a statement issued last week, it highlighted the causalities among civilians and security forces and urged Riyadh to confront its security challenges in “a manner that abides by international human rights law”.

Days later, the ministry said the government was actively seeking more information about the reports of civilian casualties and claims that Canadian-made vehicles were involved. “If it is found that Canadian exports have been used to commit serious violations of human rights, the minister will take action,” a spokesperson for department told the Guardian. He did not answer questions around what kinds of actions this could entail.

Terradyne Armoured Vehicles did not respond to a request for comment.

The allegations have prompted renewed calls for Trudeau’s Liberal government to scrap a recent decision to push forward with a 15-year contract to supply Saudi Arabia with weaponised armoured vehicles made by General Dynamics, another Ontario-based company.

Critics say the C$15bn deal, struck in 2014 by the previous conservative government, could see the vehicles – which are equipped with machine guns – used by the Saudis to crush dissent at home. Others have pointed to Canadian rules that restrict arms exports to countries with poor human rights records and prohibit exports if there is a possibility that the buyer could use the arms against its own population.

Despite these concerns, Trudeau’s Liberal government signed off on the export permits in 2016. Trudeau has since defended the decision, arguing that Canada would be seen as a “banana republic” if it scrapped the deal. “People have to know that when you sign a deal with Canada, a change in governments won’t immediately scrap the jobs and benefits coming from it,” the prime minister told the Toronto Star last year. The deal would reportedly create around 3,000 jobs in Canada.

Amid escalating concerns over human rights, countries such as Germany and Belgium have in recent years denied export applications for arms headed to Saudi Arabia. In 2015, Sweden cancelled a longstanding defence agreement with the Saudis, citing similar concerns.

This month, a high court in London ruled that the UK could proceed with arms sales to Saudi Arabia. “Saudi Arabia has been, and remains, genuinely committed to compliance with International Humanitarian Law; and there was no ‘real risk’ that there might be ‘serious violations’ of International Humanitarian Law (in its various manifestations) such that UK arm sales to Saudi Arabia should be suspended or cancelled,” the court said.

Campaigners called the ruling a “green light” for the UK to sell arms to “brutal dictatorships and human rights abusers”.

In Canada, Amnesty International pointed to the indications that Canadian vehicles are being used against civilians to call on the Liberal government to reverse its support of the billion-dollar arms deal.

“Mounting tensions and conflict in eastern Saudi Arabia, about which the Canadian government has rightly expressed public concern, further indicate how fraught it is for Canada to have authorised the sale of light armoured vehicles to Saudi Arabia at this time,” secretary-general Alex Neve said in a statement.