OTTAWA -- The federal government should have been more careful when it tweeted concerns about the arrest of human rights activists in Saudi Arabia, a former diplomat says.

Colin Robertson, vice-president of the Canadian Global Affairs Institute and a career diplomat, says "diplomacy by tweet" is a bad way to issue policy statements.

"Diplomacy by tweet is best taken with great care... as we have learned to our cost," Robertson said in an interview with CTV News.

"You cannot say in 247 characters or 400 characters the nuance that you want to capture in a diplomatic statement."

Robertson says a tweet about Saudi Arabia arresting women's rights activists is the cause of Canada's current problems with the kingdom, whose leaders took offence to the call for the activists' "immediate release."

"They felt it prejudged their judicial system," he said.

A number of human rights organizations have raised repeated concerns about the Saudi Arabian judicial system, which sentences people to lengthy prison sentences and employs corporal punishment as well as the death penalty. Amnesty International says torture remains common, and activists have been sentenced to death following "grossly unfair trials."

Former foreign affairs minister John Baird agrees Twitter was the wrong platform on which to send the message.

"This relationship has gone south and it's gone south fast, and it's not too late to rescue it," Baird said in an interview with CTV News.

"We share an important amount of interest with Saudi Arabia. They're battling the Islamic State, they're battling Iran, who has taken out the government in the neighbouring country of Yemen, and it's in our interest to work cooperatively."

Baird says he spoke for 15 minutes about women's rights when he met with the man who is now Saudi King Salman. Baird was Canada's foreign affairs minister from 2011 to 2015. He now advises several companies and has three clients who do business in Saudi Arabia.

Trudeau must fly to Riyadh to speak directly to the King or Crown Prince Mohammad bin Salman.

"You do it respectfully and face to face, and not do diplomacy via Twitter," Baird said.

Officials say Canada routinely raises human rights issues in private meetings with Saudi Arabia and noted that Freeland raised them in May during a bilateral meeting with the Saudi foreign minister. They did not directly answer whether she raised the concerns noted in the tweet before it was sent.

Speaking in Montreal, Prime Minister Justin Trudeau said the Canadian government continues to engage with the Saudi Arabian government.

"The minister of foreign affairs [Chrystia Freeland] had a long conversation with their foreign minister yesterday and diplomatic talks continue," he said.

"But as the minister has said and as we will repeat, Canada will always speak strongly and clearly in private and in public on questions of human rights."

Saudi Arabia selling Canadian assets: report

The repercussions now include Saudi Arabia’s central bank and state pension funds issuing orders to eliminate new Canadian investments "no matter the cost," according to a report by the Financial Times.

The move could explain Tuesday’s poor performance by Canadian markets, which fell due to selling activity by an unknown investor.

The reported sell-off is the latest in a series of measures taken by Saudi Arabia since the Canadian government called on the kingdom to release detained female bloggers and activists.

The Saudi government instructed Saudi nationals staying in Canadian hospitals to leave the country. More than 15,000 post-secondary students were previously ordered to leave Canada and return to Saudi Arabia.

Canada’s ambassador to the country was expelled earlier this week, while the Saudis recalled their own ambassador from Ottawa. Trade has also been frozen between the two countries.

Analysts say the moves suggest Saudi Arabia is using Canada to send a message to the rest of the West about attempts to interfere in what it sees as its internal affairs.

On Wednesday, Saudi Arabia's foreign minister shifted responsibility for resolving the dispute back to Canada, telling a news conference in Riyadh that "Canada knows what it needs to do," according to multiple reports.

Adel al-Jubeir said there's nothing to mediate in the spat, and said Saudi Arabia is considering additional measures against Canada.

"A mistake has been made and a mistake should be corrected," he said, according to a Reuters report.

The Canadian government says it continues to seek clarity from the kingdom "on various issues" and referred questions about the reported asset sell-off, as well as about the foreign minister's remarks, to the Saudi government.

"The Embassy's trade officers in addition to the wider Trade Commissioner Service are actively engaged with Canadian business interests and will continue to work with them and the relevant authorities in the coming days," Amy Mills wrote in an email to BNN Bloomberg.

Export Development Canada, a Crown corporation that provides financing and advice to Canadian exporters, says it is reviewing its position on Saudi Arabia. The commercial institution had the country listed as open for business with a low risk of political interference, the National Post said Tuesday. By Wednesday it had removed the previous assessment and noted the review is happening "in light of recent events."

With files from CTVNews.ca staff