Syrian troops were fighting to prevent rebels moving in on central Aleppo on Tuesday as the conflict in the country continues with unabated fury.

Residents and activists said rebels were clashing with government soldiers and intelligence officers at the gates of the Old City, a United Nations World Heritage site.

Troops loyal to President Bashar al-Assad also put down a jail mutiny on the outskirts of the city, killing at least eight people.

The opposition Syrian National Council said in a statement that security forces "opened fire with bullets and tear gas on the detainees at Aleppo central prison in response to a peaceful sit-in organized by prisoners because of the great injustice of which they are victims."

The report cannot be verified independently owing to restrictions on journalists in Syria.

Aleppo, a major commercial hub in the north, was long spared fighting in the 16-month upheaval affecting Syria, but clashes are escalating as rebels increase their efforts to seize the city.

Nationwide clashes

The Local Coordination Committees, which organizes opposition forces on the ground, also reported renewed shelling in parts of the capital, Damascus.

Activists said explosions and gunfire rocked the central district of Barzeh after government forces stormed the area overnight. Tanks were also seen patrolling the streets of Midan, a district the army recaptured from rebels on Friday.

Fighting was also reported in the rebel district of Rastan in Homs province as well as the Kurdish mountains in the northwest of the country.

The British-based opposition Syrian Observatory for Human Rights said the nationwide death toll across Syria by Tuesday afternoon stood at 33.

Chemical weapons warning

As the fight for Syria gains momentum, Western leaders have condemned an admission by Damascus on Monday that it has chemical and biological arms and could use them in the case of foreign military intervention.

United States President Barack Obama told veterans in Reno in the state of Nevada that Assad and his associates would be "held accountable by the international community and the United States should they make the tragic mistake of using those weapons."

UN Secretary General Ban Ki-moon said use of the weapons would be "reprehensible."

French Foreign Minister Laurent Fabius said Syria's chemical weapons were under "strict surveillance by the international community" and that their use would be unacceptable.

Some of Syria's rebels have since accused Assad of moving chemical weapons to the country's borders in a bid to pressure the international community.

Refugee crisis

Meanwhile, the humanitarian crisis in Syria is taking on giant dimensions.

A spokeswoman for the UN refugee agency UNHCR said that the number of displaced people within Syria had risen to about 1.5 million, up from a previous estimate of 1 million.

She added that more than 10,000 Iraqi refugees returned home from Syria in the past week, almost as many as the 13,000 who left in the first half of 2012.

Activists say at least 18,000 people have been killed in the uprising in Syria since it erupted in March 2010.

tj/rc (Reuters, AFP)