A second Canadian missing in China is under investigation on suspicion of “engaging in activities that harm China’s national security”, state media has reported, as tensions over the arrest of an executive at Chinese telecoms giant Huawei intensify.

Michael Spavor was “being investigated” by the Dandong city branch of China’s ministry of state security and the probe started on 10 December, according to a government news agency in northeastern Liaoning province.

Spavor is based in China and facilitates trips to North Korea, according to the Canadian foreign ministry. He met its leader Kim Jong-un and famously arranged some of retired NBA basketball star Dennis Rodman’s visits there.

Michael Spavor (L) and former US basketball player Dennis Rodman (R) arrive at Beijing International Airport from North Korea in 2014. Photograph: Wang Zhao/AFP/Getty Images

Michael Kovrig, a former Canadian diplomat, was detained by Chinese state security on Monday in Beijing, according to his employer, the International Crisis Group thinktank.

After Kovrig was held, another Canadian citizen – later identified as Spavor – contacted officials, saying he had been questioned by Chinese authorities. He later went missing.

“We have not been able to make contact with him since he let us know about this,” said Canada’s foreign minister, Chrystia Freeland, at a news conference on Wednesday afternoon. “We are working very hard to ascertain his whereabouts and we have also raised this case with the Chinese authorities. We are in touch with his family.”

Spavor and Kovrig are said to know each other, the Canadian newspaper the Globe and Mail reported.

Posts on Spavor’s social media showed friends beginning to question his whereabouts after he failed to show up to a planned visit to Seoul on Monday, the same day Kovrig is believed to have detained by security officials in Beijing. He was scheduled to be in the city, for conferences and social events, until at least Friday.

Canadian officials have been wary of potential retaliation by the Chinese government after the arrest last week of Huawei executive Meng Wanzhou in Vancouver.

In response to protests over Meng’s arrest, as well as rising anti-Canada sentiment in China, Canada has requested that China increase security for its diplomats, said a senior Canadian government official.

But the Canadian government has been unwilling to directly link Meng’s arrest with the detention of Kovrig, who is being questioned on suspicion of engaging in “activities that harmed China’s national security”, according to Chinese state-run media.

“Canadian citizen Michael John Kovrig was on 10 December investigated in accordance with the law by the Beijing State Security Bureau on suspicion of engaging in activities that harm China’s state security,” the Beijing News wrote.

Accusations of harming state security could cover a wide range of suspected crimes, and in China are often very vague when first levelled.

Kovrig is on leave from Global Affairs Canada, the department of the Canadian government that manages diplomatic and consular relations, but he is still considered an employee, said an official. However, he does not have diplomatic status.

His current employer the ICG, a thinktank focused on conflict resolution, said in an earlier statement Kovrig was detained by state security officials in Beijing on Monday night.

Diplomats in China said the apparent involvement of the secretive state security ministry, which engages in domestic counter-espionage work, among other things, suggests the government could be looking at levelling spying accusations.

However, the ICG president and chief executive, Robert Malley, said the group did not engage in such activity.

“I don’t want to speculate as to what’s behind it but I am prepared to be categorical about what’s not behind it, and what’s not behind it is any illegal activity or endangering of Chinese national security,” Malley told Reuters, before the state media report came out.

“Everything we do is transparent, it’s on our website. We don’t engage in secretive work, in confidential work.”

The Chinese foreign ministry spokesman, Lu Kang, said the ICG was not registered in China as a non-government organisation (NGO) and Kovrig could have broken Chinese law.

The foreign NGO law, which took effect in January, is part of a raft of new national security measures introduced under President Xi Jinping.

“All foreigners that come to China, so long as they respect the law, have nothing to worry about,” Lu said.

William Nee, the China researcher for Amnesty International’s East Asia regional office in Hong Kong, said Kovrig’s detention was alarming, especially as it appeared to be the first time the law has been used to detain a foreign NGO worker.

“We need to wait for the official explanation from the Chinese side, but this detention could have a chilling effect on the foreign NGO and business communities in terms of their feeling safe while travelling in China,” he told Reuters.

Guy Saint-Jacques, Canada’s former ambassador to China, was asked by the Canadian Broadcasting Corporation on Tuesday whether Kovrig’s detention was a coincidence after the arrest of Meng.

“In China there are no coincidences,” he said. “In this case it is clear the Chinese government wants to put maximum pressure on the Canadian government.”

China had threatened severe consequences unless Canada released Meng immediately and analysts have said retaliation for the arrest was likely.

Meng was granted bail by a Canadian court on Tuesday, 10 days after her arrest in Vancouver on US claims that she misled multinational banks about Iran-linked transactions caused a diplomatic dispute. As part of her release, she has provided a $10m bond – in parts cash and properties – and must wear a GPS monitoring device.

The detention of the two Canadians holds parallels to a previous spat between China and Canada. In 2014, British Columbia resident Su Bin — a Chinese citizen — was arrested by Canadian officials on accusations that he had stolen top-secret American fighter jet plans. He was then extradited and pled guilty to the charges in a California court.

Shortly after his arrest, Canadians Kevin and Julia Garret – who had lived in China for 30 years and ran a coffee shop in Dandong – were arrested by Chinese officials. Kevin Garrett was charged with espionage and spent two years in prison.