Authorities in the northern Chinese region of Inner Mongolia have arrested 52 people for spreading "internet rumours", underscoring rising ethnic tensions in the area, a New York-based human rights group reported this week.

The detainees are suspected of "deliberately stirring up ethnic relations [and] encouraging the masses to appeal for their interests in a radical way such as [organising] student strikes and protest demonstrations", the Southern Mongolian Human Rights Information Centre reported on 4 September, citing a local police statement posted late last month.

The suspects were detained for illegally distributing 1,200 pieces of information, including "internet rumours and false reports of disaster, epidemic, and police emergency", according to the statement.

Both the statement and follow- up state media reports suggest that the detentions are part of a nationwide "strike hard" campaign by the Communist party to tighten its grip on the country's online communities.

On Friday afternoon, the Inner Mongolia autonomous region public security bureau could not be reached for comment.

Ethnic tensions have long been a source of social unrest in Inner Mongolia, a resource-rich region bordering Mongolia and Russia. Government mining programmes have dealt a blow to the region's natural environment, forcing many of its indigenous nomads to abandon their traditional way of life.

Ethnic Mongolians account for less than a fifth of the region's 24 million people, and many are discontent with a perceived lack of economic opportunities in towns and cities.

In May 2011, protests rippled through the region after Han Chinese drivers killed a Mongolian herder as he attempted to block a caravan of coal trucks. Inner Mongolian authorities deployed riot police, severed communications networks and barricaded university campuses, quashing the demonstrations shortly after they began.

Regional authorities arrested another 23 people in mid-August for circulating "internet rumours" that disaster victims from south-western Sichuan province would be relocated to Inner Mongolia, the state newswire Xinhua reported.

The recent spate of detentions has coincided with a thwarted protest in Ordos, a city in the region's arid west, according to the Washington-based broadcaster Radio Free Asia.

"In Ordos, a herder died after being run over, causing a mass incident because the construction of the railway was affecting the grasslands and causing opposition among local people," Xi Haiming, the chairman of the Germany-based Inner Mongolian League for the Defense of Human Rights, told the broadcaster.