Dozens of people have been killed in fierce clashes between Syria troops and opposition fighters, mainly in the suburbs of Damascus, monitoring groups have reported.
Opposition forces and Syrian army units were locked in fierce clashes around elite Republican Guard posts in the capital, the Syrian Observatory for Human Rights (SOHR), an activist monitoring group, said on Tuesday.
"Violent clashes are taking place around positions of the Republican Guard in Qudssaya and Al-Hama," 8km from central Damascus, Rami Abdel Rahman, the head of the SOHR, told the AFP news agency.
Fighting has intensified in past weeks in and around the capital, where government buildings and security posts are heavily defended, but the violence on Tuesday was the most intense in the area, Abdel Rahman said.
"This is the first time that the regime uses artillery in fighting so close to the capital," he said.
"This development is important because it's the heaviest fighting in the area and close to the heart of the capital."
Syrian president Bashar al-Assad swore in his new cabinet on Tuesday, and in a short televised address afterwards said that the country was "in a real state of war".
"When we are in a war, all policies and all sides and all sectors need to be directed at winning this war," he said.
Al Jazeera's Rula Amin, reporting from Beirut, said that the reports of clashes in Damascus were significant as most opposition attacks on the Syrian army had previously only been overnight attacks.
"This shows how desperate rebels are to bring the fighting to capital and also how desperate the Syrian government is to keep opposition fighters back," she said.
The opposition fighters blew up an artillery gun at the entrance to Qudssaya, said Abdel Rahman.
"These suburbs are home to barracks of troops which are very important for the regime like the Republican Guard," he said.
"This is also where families of [army] officers live."
In-depth coverage of escalating violence across Syria
The SOHR reported that Syrian troops, backed by "large military vehicles", stormed the Barzeh neighbourhood of Damascus, amid heavy shooting.
Another monitoring organisation, the Local Co-ordination Committees in Syria (LCC), reported one fatality in the area as well as many other people injured as the "army stormed the neighbourhood with tanks, armoured vehicles, and a large number of soldiers".
The SOHR reported major shelling by Syrian forces on opposition fighters in al-Reef, on the outskirts of Damascus.
"Intense shelling by the Syrian regime and also intense clashes with rebels fighters in [Al-Hamaeh town]. Also, sounds of explosions in the suburbs of Doumar and Qudssaya, areas outside of Damascus," the observatory said.
The Revolution Leadership Council of Damascus reported seven fatalities and 13 people injured in Al-Hamaeh.
"Continuous ... shelling, sounds of gunfire, and snipers on building rooftops [in Al-Hamaeh]," it said.
"Telephone landlines and cell phone lines are disconnected, in addition to electricity cut off. Military reinforcement is on the way to the area now."
Elsewhere in the country, the town of Saraqeb in Idlib province, in the northwest, was hit by "more than 20 shells in half an hour" after midnight, according to the observatory, which gave no casualty toll.
Syrian activists in the outskirts of Aleppo also said that 280 soldiers defected in Idlib near the main highway leading to Aleppo, also on Tuesday. They said there were clashes between the defectors and the Syrian army and that one helicopter had been shot down and six tanks destroyed.
The LCC reported that there has also been fierce fighting in old Homs. "Fierce rocket bombing in Old Homs neighbourhoods, and massive explosions from bombing," it said.
At least 95 people, including 61 civilians, were killed on Monday as the army pounded rebel strongholds and other towns and cities, according to activists,
The SOHR, which is based in the UK, says the government's suppression of the uprising, which began in March last year, has cost more than 15,000 lives.
Meanwhile, Ammon, a local news agency in Jordan, reported on Tuesday that a Syrian airforce team was to visit a Jordanian airbase to collect the jet of an air force pilot who defected on Thursday.
Hassan Merie Al Hammadeh made an emergency landing in the MiG 21 fighter jet near Mafraq, requesting political asylum in Jordan.
Syrian activists cited the act as the first such defection involving an aircraft since the start of the uprising.
Russian President Vladimir Putin was also due in Jordan on Tuesday to hold talks with King Abdullah focusing on political developments and changes in the Middle East.