Swedish activist Peter Dahlin, who was detained in China on charges of damaging national security, has been released and deported.

The 35-year-old has been held since early January amid a crackdown on human rights lawyers and activists.

Last week Peter Dahlin appeared on state media apparently confessing to breaking the law through his organization’s support of local Chinese rights lawyers.

The Swedish embassy confirmed Peter Dahlin had left China but gave no further details.

Sweden’s foreign minister welcomed Peter Dahlin’s release, but expressed concern about another Swede in Chinese detention.

More than 280 lawyers, legal assistants and associates were detained in a seemingly orchestrated government campaign last year – most have since been freed, but others now face trial while the whereabouts of others are still unknown.

Such moves contradict China’s implementation of reforms explicitly aimed at strengthening the rule of law, say correspondents.

Peter Dahlin is the founder of Chinese Urgent Action Working Group (China Action), which describes itself as a legal aid organization.

It provides assistance to uncertified “barefoot” lawyers who provide legal aid in rural areas, and provides direct help to disadvantaged groups and individuals who have experienced rights violations.

The group had said Peter Dahlin was detained on 4 January while en route to the airport for a flight to Thailand.

Last week, in a report on state television, Peter Dahlin appeared to confess to helping the Beijing law firm Fengrui – a number of the company’s lawyers have recently been charged with subversion.

Peter Dahlin said he had violated Chinese law, caused harm to the Chinese government and hurt the Chinese public.

China Action called the report “absurd” and said the confession appeared to be forced.

The group’s US-based co-founder Michael Caster tweeted that Peter Dahlin’s Chinese girlfriend, Pan Jinling, was also no longer in detention “but, contrary to some assertions, has not left the country”.

Sweden’s Foreign Minister Margot Wallstrom said she remained “greatly concerned” about the status of detained Swedish national Gui Minhai.

Gui Minhai is one of five people linked to a Hong Kong publishing house to disappear in recent months. He vanished while on holiday from Hong Kong in Thailand in October 2015.

He also appeared on Chinese TV earlier this month, saying he had voluntarily handed himself over to the authorities over a drink-driving fatality years ago.

The case has sparked protests in Hong Kong from those who believe they were kidnapped by China and are being held because of allegations in a book they were working on, critical of the mainland.

Margot Wallstrom said Sweden’s “efforts to get a clear picture of his situation and the possibility to visit him continue with undiminished force”.