China's Inner Mongolia 'under heavy security', 30 May 2011 Last updated at 08:36 GMT

Rights groups said 2,000 students protested in Xilinhot last week

Chinese authorities have tightened security across the province of Inner Mongolia after days of unrest, rights groups and residents say.

Hundreds of riot police armed with batons are patrolling the main square in the provincial capital, Hohhot.
Ethnic Mongolians began to protest after a farmer was run over and killed.
Reports say the herder was trying to protect his land when he was run down on 10 May by a van driven by an ethnically Han Chinese man.
The New York-based Southern Mongolian Human Rights Information Centre said more demonstrations had been planned for Monday.
The centre described the situation in many parts of Inner Mongolia as martial law.
Amnesty International also described the situation as martial law and called for restraint from the authorities.
"Given the heavy-handed repression of similar protests in other regions, like Xinjiang and Tibet, there are real grounds for concern about the situation in Inner Mongolia," said Catherine Baber, Amnesty International's Asia Pacific deputy director.
Residents told the Associated Press that police were out in force, and the internet had been cut off.
"There's no point in going to the internet cafes since they have suspended business because the internet is down there too," said a waitress at the Laozhuancun restaurant, in the city of Chifeng.
A university worker in Hohhot told Reuters that three entrances to the institution had been sealed off by police.
Arrests The demonstrations last week are thought to be the region's largest in 20 years, involving hundreds of ethnic Mongolians.
The Xilinhot government has not commented on the protest.
But the government confirmed last week that two Han Chinese were arrested for murder.
Some analysts believe one of the men is a suspect in the killing of the farmer on 10 May.
On Friday, provincial Communist Party chief Hu Chunhua met students and teachers and promised that anyone found to have committed a crime would be brought to justice, according to the state-run Inner Mongolian Daily.
"Please rest assured that the suspects will be punished severely and quickly," Mr Hu said, without specifying which cases he was talking about.
The population of Inner Mongolia is predominantly Han Chinese.
But the province is still home to an estimated five million ethnic Mongolians, and many of them say their nomadic pastoral existence is being threatened by the growth of mining projects in the mineral-rich region.