Six people were killed in Yemen on Sunday when government troops opened fire on an opposition rally in the capital Sana'a, broadcaster Al Arabiya reported.
The protesters were calling for the ouster of President Ali Abdullah Saleh when snipers positioned on rooftops of buildings fired on them, according to the opposition website Mareb Press.
Scores of people were also injured, it added. There was no immediate comment from the authorities, DPA reported.
Meanwhile, an unspecified number of people were injured Sunday in renewed clashes between Saleh's Republican Guard forces and loyalists of tribal leader Sheikh Sadiq al-Ahmar in the Sana'a neighbourhood of al-Hasaba, Arab media reported.
In May, confrontations between government forces and armed al-Ahmar tribesmen left some 300 people dead on both sides, with more than 1,000 wounded.
Al-Ahmar has recently vowed not to allow Saleh to keep power.
Saleh is staying in Saudi Arabia recovering from injuries he sustained in an attack on his palace in Sana'a in June.
Since February, millions of Yemenis have been taking to the streets demanding Saleh, who has been in power for 32 years, to step down.