BEIJING, Sept 24 (Reuters) - Chinese paramilitary police swept through a busy bar district in Beijing, detaining about 20 African nationals suspected of selling drugs, witnesses said.

The raid at midnight on Friday in fashionable Sanlitun, also home to many embassies, came as police tighten security ahead of a Communist Party meeting in mid-October and next year's Olympic Games.

"The paramilitary police sealed off the street at both ends, then moved in," said a witness surnamed Wang.