Sanaa, Yemen (CNN) -- The largest opposition bloc Yemen will hold protest rallies on Tuesday, the group announced Sunday.
Leaders of Yemen's Joint Meeting Parties are calling on the group's followers to protest in support of anti-government demonstrators throughout the country. Those protesters, inflamed by the violent crackdown on protesters in Aden on Friday, are calling for President Ali Abdullah Saleh's resignation.
This is the first time that the opposition has called on its supporters to take to the streets since February 3, which had been branded a day of rage, a common term for the mass protests that have spread across the Middle East and parts of Africa.
Thousands of people continued to protest outside Sanaa University on Sunday, insisting on Saleh's resignation. Representatives said the youth-dominated sit-in will remain until their demands are met.
On Saturday, leaders of two prominent tribal groups, the Hashid-dominated National Solidarity Council and the Baqil tribe, said they would send members to join the protests calling for Saleh's resignation.
The announcements come in the aftermath of violent confrontations between security forces and protesters on Friday, when
thousands of anti-government protesters demonstrated in Sanaa, Aden and elsewhere.
The clashes left four people dead and 26 wounded, according to medical officials. Amnesty International said it had reports that 11 people died in Friday's protest, bringing the overall death toll since protests began to 27.
Witnesses said the victims of Friday's violence were anti-government demonstrators hit by gunfire when security forces shot into crowds of protesters in the city's Mualla district after 10 p.m. Friday. The official Saba news agency, citing an unnamed security source, said the government denied protesters had been shot.
Saleh did not appear to be wavering in his intention to remain in office. He spoke to military leaders Saturday, saying there was a plot against Yemeni unity and saying protesters in Aden were causing damage out of "selfishness."
And two human rights groups criticized the government for what they said were systematic abuses against protesters and journalists.
Amnesty Interneational said that it has received reports that Yemeni security officials have prevented people from taking wounded people to the hospital.
"Events in Yemen are taking a serious turn for the worse and the Yemeni security forces are showing reckless disregard for human life," Philip Luther, the group's deputy director for the Middle East and North Africa, said Saturday.
Human Rights Watch issued also issued a statement Saturday accusing Yemen's government of harassing, attacking, or allowing attacks on 31 journalists to stop them from reporting on the protests.
"Beating up journalists is a blatant attempt by the authorities to prevent the Yemeni people and the world from witnessing a critical moment in Yemen," said Sarah Leah Whitson, director of the group's Middle East and North Africa division.
Saleh has ruled Yemen since 1978 and has promised not to run for re-election in the next round, but protesters have increasingly argued that nothing less than his resignation will be acceptable to them.
The country has been wracked by a Shiite Muslim uprising, a U.S.-aided crackdown on al Qaeda operatives and a looming shortage of water. High unemployment fuels much of the anger among a growing young population steeped in poverty.
The protesters also cite government corruption and a lack of political freedom.