It is rare for China to accuse foreigners of national security offences, which can carry heavy penalties, although some have occasionally been accused of spying.
Peter Dahlin was detained more than a week ago on his way to Beijing's international airport, the Chinese Urgent Action Working Group which he works for said in a statement.
Authorities had prevented embassy officials from speaking to him, it added, and his Chinese girlfriend had also disappeared.
Dahlin's organisation, also known as China Action, said it supports "barefoot" lawyers who provide pro-bono legal aid to grassroots victims of rights violations, from demolition and eviction to arbitrary detention.
"Peter has been arbitrarily detained on spurious accusations," it said, referring to a "six-month long assault on the country's human rights lawyers".
Under President Xi Jinping the ruling Communist Party has stepped up a campaign against outspoken academics, lawyers and human rights activists, which has seen hundreds detained and dozens jailed.
Detention of foreigners on national security grounds is rare in China, though Japan said four of its citizens were held last year and accused of spying.
US businesswoman Sandy Phan-Gillis has been held for six months in China over alleged espionage, supporters said in September.
A Canadian Christian couple who ran a coffee shop in the Chinese border city of Dandong were detained on espionage charges in 2014. The wife was later granted bail.
China passed a new "national security" law in July that was criticised by rights groups for the vague wording of its references to "security", which raised fears it could give police wide-ranging discretionary powers over civil society.
Chinese state-run media often accuse foreign NGOs of undermining national security and trying to foment "colour revolution" against the Communist Party.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
