SANAA - As anti-government protests continued rattling Yemen amid tightened security, the UNICEF on Tuesday warned against risks of attacking schools and pushing students in political wrangling.

At least one protester died of gunshot wound in clashes with security forces on Tuesday night outside Sanaa University, while another 30 protesters were seriously injured and 40 suffered suffocation caused by tear gas in Yemen's capital, police officer and eyewitnesses said.

Three eyewitnesses said one protester was killed by gunshot he sustained during the clashes, in which security forces fired live ammunition and tear gas bombs.

They said 30 protesters were seriously wounded by gunshots and rubble bullets and about 40 others were suffering suffocation of tear gas.  

The shootings erupted over a dispute between the policemen and the protesters who sought to expand erecting tents in front of the university's main gate, a police officer said on condition of anonymity.

He said another group of protesters tried to erect more tents and supply more food without the policemen's permission, who are in charge of protecting the sit-in protest.

"The policemen then prevented the protesters from joining in the sit-in after they refused to accept the routine inspection, and then those protesters attacked the security soldiers and forcibly attempted to join in the protest, some of whom tried to take the rifles of the soldiers," the official said.

"The security soldiers then opened fire into air and fired rubble bullets and gunshots to defend themselves," he added.  

In the Central Prison in Sanaa, at least four prisoners were shot dead, while nearly 20 other prisoners were wounded after a protest calling for the resignation of President Ali Abdullah Saleh turned into riots on Tuesday, an official of the Yemeni Interior Ministry told Xinhua.

Elsewhere in the southern province of Ibb, a 12-year-old protester Omar Abdulrahman died in hospital of gunshot from government backers who raided the protesters' sit-in on Tuesday, according to a local councilman.

UNICEF said on Tuesday that reports from Yemen's southern port city of Aden confirmed that anti-government demonstrators threatened to burn down schools if teachers and students do not join in their protests.

"Monday's reports from Aden read that a number of schools in al- Mansoura and al-Mualla districts of Aden province were attacked by demonstrators," it said in a press release issued by the organization's office in Sanaa.

"Recent reports also showed that children and adolescents were involved or were even harmed in direct confrontations in the past weeks. Such reports are of great concern of UNICEF," it said.    

Yemeni Minister of Education Abdul-Salam al-Jawfi "asserted on Tuesday that the ministry will punish anyone who involves children in such disputes, calling upon all to respect schools," the state- run Saba news agency reported.

In power for 33 years, President Ali Abdullah Saleh earlier refused an opposition roadmap, which offered him a peaceful transition of power by the end of this year.

Protests swelled across Yemen on Tuesday, as Saleh renewed his call for a national-dialogue conference with the opposition, Saba reported without telling when the conference was scheduled for.

"The opposition's rotating President Yaseen Saeed Noman rejected Saleh's call, saying the decision now is up to the street protesters," a senior aide to the opposition coalition told Xinhua.

As a precautionary against potential spreading unrest, the government deployed Tuesday heavy security forces and armored vehicles around a sit-in area of thousands of protesters camping outside Sanaa University's campus for two weeks after the protesters vowed to march towards the presidential palace on March 11 to urge for the resignation of Saleh.

Security sources outside the campus said around 20 professors of Sanaa University joined on Tuesday in the anti-government sit- in. Tanks were stationed in main streets leading to the presidential palace in the capital Sanaa, while armored vehicles were sent to guard foreign embassies, banks and governmental facilities, a security official told Xinhua on condition of anonymity.

Security forces were also deployed in nearly all major troubled cities, especially in the southern provinces, where anti- government sentiments are simmering, according to security sources.

Inspired by Tunisian and Egyptian revolutions, protests rallies reportedly escalated in the southern provinces of Dhamar, Ibb, Taiz, Al-Dhalee, Al-Baydaa, Aden, Abyan, Shabwa and Hadramout since February 11.

Besides escalating protests, the government struggles to cement a fragile ceasefire deal with a Shiite rebellion in the north and to quell a growing separatist movement in the south while mounting resurgent al-Qaida regional group rampaging through the country's major cities.

As the security agencies have been busy in protecting protest rallies and preserving local and foreign interests since February 11, the resurgent al-Qaida in the Arabian Peninsula (AQAP) killed 16 security and military personnel during the nearly month-long period, according to a Xinhua tally.