BEIJING — A Chinese court sentenced the nephew of legal activist Chen Guangcheng to more than three years in jail for assault in a hurried, suddenly announced trial Friday that his parents were barred from attending.

The punishment against Chen Kegui is seen as retaliation by local officials angered by Chen Guangcheng’s daring escape from house arrest in April. Chen, who is blind, fled to the US Embassy and set off a diplomatic tussle between Beijing and Washington that embarrassed the central government.