A court in Tianjin China has sent a Christian leader from an underground church to more than seven years in jail in a crackdown on human rights activists.

Hu Shigen was sent to prison on charges of subversion, becoming the second person to be jailed in two days for subversion by the court 100 kilometers (60 miles) south-east of Beijing, International Business Times reported.

It cited China State media as reporting that Hu pleaded guilty in Tianjin to "damaging national security and harming social stability."

The international community has referred to the cases as a government attempt to silence critics, IBT said.

Around 300 lawyers and activists have been rounded up since last year as part in the nationwide crackdown, the BBC reported on Aug. 3.

Out of them, two activists are currently facing trial while around 20 still remain in detention.

Hu was the latest to be jailed by Chinese courts during a week of activist trials and public confessions that have shocked international observers, The Guardian reported.

He was sentenced to seven years and six months' imprisonment and derived of political rights for five years.

Prior to this jail term, Hu had spent 16 years in prison for other political offences, including sharing leaflets about China's 1989 crackdown on protesters in Tiananmen Square.

After the 1989 Tiananmen Square crackdown, he co-founded the China Freedom and Democracy Party, The Los Angeles Times reported.

In the early 1990s, he wrote articles and made fliers calling for the commemoration of the 1989 victims, but when he devised a plan to fly a drone to release them over Tiananmen Square in 1992, he was arrested.

In 1994, he was sentenced to 20 years in jail for "organizing and leading a counter-revolutionary group" and "engaging in counter-revolutionary propaganda and incitement."

Hu was released in 2008 after 16 years and resumed his activism. He was detained again in 2011 and 2014.

Hu's latest case came in a series of court sentences against rights activists and lawyers that observers claim have almost zero credibility, The Guardian said.

Police swooped on them more than one year ago, holding them secretly detention and later arrested several others on subversion charges.

Families of those arrested say they had no access to their relatives.

China Human Rights Defenders, a non-profit organization headquartered in Washington DC, said the detentions and trials make a mockery of China's officially-stated commitment to rule of law.

On July 31, a lawyer from the Fengrui firm, Wang Yu, in a video interview was said to blame "foreign forces" for influencing the law firm's activities and using her family to attack the Chines government.

Yu has now been released on bail, however, some experts believe that she agreed to do the interview in order to protect her son and husband, the latter of whom is in detention and also faces charges of subversion.