Tens of thousands of demonstrators are rallying in Yemen's capital, Sana'a, where many protesters are calling for an end to President Ali Abdullah Saleh's 32-year rule.
Protesters took to the streets after Friday prayers. Government opponents gathered near Sana'a University, the site of a string of anti-government demonstrations this week.
Meanwhile, Reuters news says supporters of Mr. Saleh are rallying elsewhere in the capital. Demonstrators also gathered Friday in the southwestern city of Taiz.
On Thursday, Yemen's state-run media said President Saleh had ordered security forces to prevent any clashes between pro- and anti-government protesters. He also urged both sides to take precautions against those who may try to infiltrate the protests and incite violence.
At least 12 people have died in Yemeni demonstrations since the protests began earlier this month.
Clashes took place on Tuesday near Sana'a University when attackers using guns and other weapons tried to disperse the protesters, who have been camping out at the site for days.
On Wednesday, at least seven members of parliament submitted their resignations from the ruling party to protest the government's violent response to the demonstrations. They said they would form an independent bloc in the legislature.
Some information for this report was provided by AP, AFP and Reuters.