SANAA/ADEN (Reuters) - Yemen's opposition rejected an offer for a unity government on Monday, saying it would stand with the tens of thousands of protesters demanding an end to President Ali Abdullah Saleh's 32-year rule. The move came as violence spiked against security forces in the south. Local officials said gunmen killed two soldiers in successive attacks, and a prison riot killed one inmate and wounded two guards as four prisoners escaped. Saleh, a US ally against Al-Qaeda's Yemen-based wing, has been struggling to quell daily protests that have swept across the impoverished Arabian Peninsula state, leaving 24 people dead in the past two weeks. On Monday, tens of thousands of protesters gathered across Yemen, from the capital Sanaa to disparate regions where separatists or Shia rebels hold sway, chanting slogans such as "No dialogue, no dialogue. You leaving is the only option." Saleh has been trying to rally support from key tribal groups and military leaders and on Monday expressed willingness to form a unity government at a meeting with religious leaders, a source present at the meeting told Reuters. Yemen's opposition, already planning country-wide demonstrations for a billed "Day of Rage" on Tuesday, said it would not accept such a proposal. "The opposition decided to stand with the people's demand for the fall of the regime, and there is no going back from that," said Mohammed al-Sabry, a spokesman for Yemen's umbrella opposition coalition, the Joint Meeting Party. Opposition to Saleh gained steam as students and activists took to the streets since January, galvanised by successful uprisings in Egypt and Tunisia. The activist movement regained support last week from the traditional political opposition, which dropped planned talks with Saleh. On Monday, the Sanaa protesters' ranks swelled as tribesmen and Islamist groups also joined the rallies. "It seems that within some tribal circles there are elements who think Saleh's days are numbered and they would be better pinning their colours to a different mast," said Philip McCrum, an analyst at the Economist Intelligence Unit. Yemen is already teetering on the brink of state failure - one in two people own guns, 40 percent of the population lives on less than $2 a day and a third face chronic hunger. In Sanaa, where the government exerts the most control, around 5,000 protesters camped out in front of Sanaa University, shouting anti-Saleh slogans in the morning and chewing narcotic qat leaves in their tents and singing nationalist songs in the afternoon. They have been there for over a week. "The president has made a lot of promises and he has not delivered. We are desperate," said Ahmed al-Muwallad, an unemployed graduate of a university pharmaceutical programme. Naji al-Anisi, 19, is a soldier in the army but joined protesters camped out at Sanaa University a week ago. "I eat two meals a day, just yoghurt and bread. But it's ok if it leads to freedom from this regime." Security forces set up road blocks around the protest camp in Sanaa to frisk those seeking to join the sit-in. Police were trying to prevent food from entering the area in an effort to choke off supplies. Police also blocked a convoy of around 1,000 protesters leaving Taiz in an attempt to reach Aden, where protests have lead to the fiercest clashes between police and demonstrators. Around 10,000 protesters held to their two-week camp out in Taiz, 200 km (125 miles) south of the capital, while thousands rallied in the northern cities of Ibb and Hudeida. Aden's sit-in on Monday of a few thousand people has so far been peaceful, a Reuters witness said. But unrest remains high in the south. A local official said two soldiers were killed and 11 wounded in attacks by armed men in the flashpoint Abyan province. The official blamed Al-Qaeda. In further turmoil, a prison riot broke out in the southern province of Mahra, near the border with Oman on Sunday. One inmate was killed in clashes with police. Four prisoners escaped and two guards suffered burns.