Chinese authorities have detained miners who mounted a large demonstration against unpaid wages, residents said Friday, as officials struggle to control labor protests fueled by slowing economic growth.

Police have held more than 30 of the several thousand miners who marched through the northeastern city of Shuangyashan while on strike last weekend, a former mine company worker surnamed Gao told AFP.

China has vowed to cut some two million jobs in its coal and steel industries, which suffer from massive overcapacity. Slowing economic growth has also led to more strikes in construction and manufacturing.

The ruling Communist party tends to clamp down on all forms of public protest and organised strikes, which it sees as a challenge to its rule.

The demonstration which began on Saturday saw large crowds fill the streets, striking miners hold large banners demanding back pay, and police clashing with protesters.

Shuangyashan, like many other cities in the province of Heilongjiang, is heavily dependent on the coal industry.

Gao said that police detained about 30 people at the weekend, with an unspecified number of further detentions occurring this week.

A Shuangyashan mine worker surnamed Chen told AFP on Friday that his colleagues were still owed more than 60 percent of wages due between 2014 and 2015.

Workers who organized a strike had been detained, he said, adding: "The miners don't dare protest any more".

Both refused to give their full names for fear of reprisals.

"I will soon be detained myself," Chen said in a telephone call, to the sound of shouting in the background.

Police in Shuangyashan did not answer calls seeking comment from AFP.

Authorities in other parts of China have also reportedly clamped down. The city of Langzhong in Sichuan province, in the southwest, held a "public sentencing" for construction workers found guilty of "endangering public officials" during protests over unpaid wages, the state-run Beijing News reported.

Eight workers were sentenced to between six and eight months in jail at the ceremony on Wednesday, with pictures showing the suspects paraded on a state in front of a crowd, chaperoned by uniformed police and at least one gun-toting guard.