Sana'a, Yemen  - Yemeni authorities on Thursday released 12 prominent opposition activists in the country's south accused of instigating civil disorder through a string of violent protests in several southern cities, opposition sources said.

The sources told Deutsche Presse-Agentur dpa the men were released after President Ali Abdullah Saleh granted them pardons.

They said pardons included three senior members of the opposition Yemeni Socialist Party (YSP) brought to a state security court in June. Hassan Baoum, Yahya Al-Shouaibi and Ali Al-Gharib, were charged with instigating civil disorder and strife.

Authorities have blamed the wave of protests on the YSP, the former ruling party in southern Yemen. At least 13 people were killed and more than 70 were injured in clashes with security forces.

In the latest and most violent series of demonstrations, thousands of disgruntled youths took to the streets in April and May over what was claimed to be discriminatory army recruiting policies against southerners.

Groups representing more than 60,000 people who had retired from army and government jobs in southern Yemen have also staged a series of protests in the past 12 months demanding more rights and better services. Most of the retirees insist they were forced out of their jobs.

Other demonstrations have been staged to denounce rising prices in Yemen, one of the world's poorest countries, and demand better public services.

Southerners often complain of discrimination since a 1994 secessionist bid was crushed by northern forces of president Saleh. (dpa)