Monitored, scared, and made to feel like criminals, the women's only offence is to be married to lawyers and activists detained by China's Communist authorities. But a year after their husbands disappeared, they are defiant.

The men represented some of China's most vulnerable people until they were held in a crackdown last year that swept up more than 200 attorneys and rights campaigners.

Around a dozen are still being held in near total isolation and accused of subverting state power, which carries a maximum sentence of life in prison, while their spouses are subject to constant surveillance.

This week five of them donned dresses emblazoned with their husbands' names and marched to a national prosecutors' office in Beijing -- surrounded by dozens of police.

They clutched handwritten letters of complaint, accusing authorities in Tianjin -- where all but one of the men are being held -- of a litany of procedural errors.

The women emerged disappointed, still holding their letters, after officials refused to even read them.

Authorities "limit our freedom by stalking us", said Wang Qiaoling, whose husband Li Heping is among those held.

"We have to creep around like criminals."

A group of diplomats looked on, a sign of the concerns that the crackdown has sparked internationally. The EU and the US have called for the lawyers' release.

Under President Xi Jinping, China has tightened controls on civil society, and the 709 crackdown -- named after the date of the first disappearance on July 9 -- represents its largest-scale operation in years.

The UN High Commissioner for Human Rights described the detentions as "worrying", but Beijing routinely dismisses such complaints as interference in its internal affairs.

- 'Depression and fear' -

China's ruling Communist party has repeatedly pledged to implement the "rule of law", but analysts say the crackdown shows the limits of that promise.

The country's courts are tightly controlled by the ruling party, with forced confessions often used as evidence and guilty verdicts delivered in more than 99.9 percent of criminal cases.

Over the past decade a few hundred lawyers, sometimes with official encouragement, used the courts to seek redress -- sometimes successfully -- for what they considered egregious rights violations.

They include victims of forced demolitions, illegal "black jails", dissidents jailed for their writing, and others detained for practising religion.

Beijing law firm Fengrui, which has defended victims of sexual abuse, members of banned religious groups and dissident scholars, was at the centre of the 709 crackdown, with five of its staff still held.

The detainees have been denied access to their families or independent defence lawyers.

Li Wenzu, wife of Fengrui lawyer Wang Quanzhang, said she had a security camera installed outside her front door and volunteers on constant watch outside.

"We are scared that if we plan to do anything together, they will detain us at home, so we leave home days in advance. We stay at hotels," she said.

Officials from China's secretive ministry of state security two months ago attempted to persuade her to record a video imploring her husband to admit guilt.

She declined the offer.

- On the road -

State broadcaster CCTV said last year the detained lawyers tricked clients and "created a nuisance" in court by arguing with officials, making recordings and taking photographs.

State media branded Fengrui a "criminal organisation" whose staff had "staged open defiance inside the courtroom and on the internet".

Chen Guiqiu said she had been banned from leaving mainland China since her husband Xie Yang was held.

"It's the same for all of us. I was told it's because of a threat to state security. I don't understand how I can be a threat to state security," she said.

The 709 detainees also include activists who organised protests outside courthouses.

Li Ermin, whose 55-year-old husband Zhai Yanmin was held, said Beijing police beat her after she travelled to nearby Tianjin to try to locate him.

Fan Lili said her cash savings and bank cards had been confiscated after her activist husband Gou Hongguo was detained, and police pressured her landlord to force her and her newborn baby to move out of their flat.

Police in Beijing and Tianjin did not respond to requests for comment from AFP.

Prosecutors are still considering whether to formally indict the men, their wives said. If they go ahead, the detainees are almost certain to be convicted and sentenced to lengthy prison terms.

"Now I'm always on the road," Fan said, boarding a clattering subway train that took her towards her next, secret destination.

"I never thought things could be this scary."