The offer by the U.S.-backed Ali Abdullah Saleh — which opposition groups swiftly rejected — came as protests calling for his ouster continued in at least four cities around the country for the 11th straight day.

A health official in the southern city of Aden said Sunday that a 16-year-old boy died the night before from wounds suffered at a protest, bringing the countrywide death toll to eight since the protests began.

Saleh’s rule continues to show signs of resilience in the face of the sustained protests, that have seen security forces and regime supporters battling demonstrators, mostly university students. The Yemeni regime, however, is not doing as well in the south of the country, where resentment of Saleh’s rule is far more entrenched and a secessionist movement is steadily gaining strength.

There have been deadly clashes there between protesters and security forces using live ammunition, rubber bullets and tear gas. South Yemen used to be an independent nation, but became united with the north in 1990. An attempt to secede by the south in 1994 was brutally crushed by Saleh’s army and allied tribesmen.

Yemen is a tribal society where almost every adult male has a firearm. A decision by the country’s major tribes to take sides in the standoff between Saleh and his critics could decide the president’s fate.

Protests continued Sunday, with 3,000 university students marching in Sanaa, the Yemeni capital. Demonstrations were also held in Aden’s Mansoura district, the town of Taiz and the province of al-Hadida.

The protests pose the most serious challenge to Saleh’s rule to date.

He has already made a series of concessions, pledging that his son would not succeed him and that he would not seek another term in office. On Sunday, he repeated his offer for negotiations.

“Dialogue is the best means, not sabotage or cutting off roads,” Saleh, in office for more than 30 years, told a news conference. “I am ready to sit on the negotiating table and meet their demands if they are legitimate,” said the Yemeni leader, who warned against “infiltrators” seeking to divide Yemenis and sabotage their country.

A group of opposition parties refused in a statement Sunday to engage in dialogue while security forces continued to suppress demonstrations.

“No dialogue with bullets, clubs and thuggery,” it said.

On Saturday, riot police fired on marchers in Sanaa, killing one and wounding five.

A total of eight people have been killed since the unrest began.

The protesters seek to oust Saleh, a key U.S. ally in the fight against al-Qaida, and have been inspired by uprisings in Egypt and Tunisia.

Marching students on Sunday burned the flag of Saleh’s party and tore up photos of the president. Some wrote “Get out! Get out!” on the sidewalk, while others carried signs reading “Get out Ali for the sake of future generations.”

Riot police surrounded them to keep them in a square in front of the university but did not intervene.

Past protests were often attacked by government supporters, degenerating into riots.

Saleh’s regime is one of several in the Arab world currently coming under popular pressure to reform or step down. Since uprisings in Tunisia and Egypt toppled the two nation’s autocratic leaders, Bahrain, Jordan, Yemen, Libya and Algeria have been gripped by anti-government protests.

In the southern city of Aden, police and army redeployed throughout the city overnight after an apparent retreat in the face of protests the day before.

Security forces had been instructed to divide up the city and prevent movement so demonstrators could not organize, a security official said.

And a health official said a 16-year-old boy had died Saturday night from injuries sustained during a demonstration, bringing the city’s death toll in recent days to four.

Security officials and activists both said about 80 people had been arrested in the city.

Officials spoke on condition of anonymity because they were not authorized to speak to the media.