Chinese officials have prevented the founder of an outlawed reform group, Peng Ming, from crossing a checkpoint into Hong Kong on his way to the United States for a lecture tour.

A Hong Kong based human rights group the Information Centre of Human Rights and Democratic Movement in Chinasaid that Mr Peng was stopped by officials who said there were problems with his passport and that he would have to return to Beijing.

The group of intellectuals he founded earlier this year, known as the China Development Union, organised discussion groups in Beijing on political reform until it was banned last week.