Syrian troops on Friday heavily shelled a rebel-held neighborhood in the flashpoint central city of Homs as the military appeared to be readying to storm the area, activists said.
Also, U.N. observers entered an area where a massacre was reported this week, an activist said Friday. The monitors were stopped and fired upon Thursday.
The Britain-based Syrian Observatory for Human Rights and the Local Coordination Committees had no immediate word on casualties from the shelling of the Khaldiyeh neighborhood in Homs. Amateur videos posted online showed a small white plane, apparently a drone, flying over Homs.
"Khaldiyeh is being subjected to five to 10 shells a minute in the worst shelling since the revolution began," the Observatory said in a statement Friday. "It seems they are trying to enter it today."
Homs has been one of the hardest hit regions in Syria since the uprising against Assad's regime began in March last year. The U.N. said several weeks ago that more than 9,000 people have been killed since the crisis began while activists put the number of dead at about 13,000.
Amateur videos showed missiles exploding into balls of flames in the crowded concrete jumble of homes, in cracking, thundering crashes that sent plumes of menacing, heavy gray smoke over Homs. The videos suggested the attack began at dawn, as birds chirped, roosters crowed, and the sun cast a yellow glow.
In one video, the missiles came in rapid succession, four exploding in less than a minute.
Friday's violence came two days after reports of mass killing in the nearby province of Hama, where about 80 people, including women and children, were shot or stabbed. Leith Al-Hamwy, an activist and resident of Mazraat al-Qubair told The Associated Press that a group of observers entered the area, first visiting a cemetery where some of the dead were buried, continuing to the site of the mass killing. In Geneva, International Committee of the Red Cross spokesman Hicham Hassan told reporters Friday that the humanitarian situation in Syria was worsening.
"Currently the situation is extremely tense, not only in Houla, not only in Hama, but in many, many places around the country," he said referring to the string of villages known as Houla, where more than 100 people were massacred last month. The opposition and the regime blamed each other for the Houla massacre.
Hassan cited the countryside around the northern city of Idlib, suburbs of the capital Damascus, the eastern province of Deir el-Zour and the coastal region of Latakia as those targeted in the latest attacks
In Brussels, Kristalina Georgieva, European commissioner for humanitarian aid, talked about the Syrian crisis and EU aid saying, "we're talking 1 million vulnerable people who need humanitarian assistance."
"Between 200,000 and 400,000 are internally displaced ... and we have 95,000 refugees in Turkey, Lebanon and Jordan primarily," she said adding that there are more than 600,000 Iraqi and Palestinian refugees in Syria.
Also Friday, activists reported anti-government protests in different areas, including the northern provinces of Idlib and Aleppo, the southern region of Daraa and the suburbs of the capital, Damascus.
Syria's state-run media said armed "terrorist groups" attacked military units charged with protecting al-Omar oil field of al-Furat Oil Company in the oil-rich city of Deir Ezzor province. The official news agency SANA said several gunmen were killed in the Friday attack.
SANA also said a car bomb in the Damascus suburb of Qudsaya killed three policemen, while another explosion in the northern city of Idlib killed two soldiers and three civilians.
It was still not clear if observers have entered Mazraat al-Qubair, where activists said dozens of people, including women and children, were killed on Wednesday. A team that tried to reach the area on Thursday was fired on.
Activists said the Sunni village is surrounded by Alawite villages. Alawites are an offshoot of Shiite Islam and Assad is a member of the sect, while the opposition is dominated by Sunnis.
A government statement Thursday on the state-run news agency SANA said "an armed terrorist group committed an appalling crime" in Mazraat al-Qubair, killing nine women and children. It said residents appealed for protection from Hama authorities, who sent security forces who went to the farm, stormed a hideout of the group and clashed with its fighters.
As reports emerged about Mazraat al-Qubair, which would be the fourth such mass killing of civilians in Syria in the last two weeks, the United States condemned Assad, saying he has "doubled down on his brutality and duplicity."
U.N. patrols in Syria have on several instances been deliberately targeted with heavy weapons, armor-piercing ammunition and a surveillance drone, U.N. Secretary-General Ban Ki-moon told the Security Council, according to a senior U.N. official. The official, speaking on condition of anonymity because Thursday's council meeting was closed, said Ban also reported repeated incidents of firing close to U.N. patrols, apparently to get them to withdraw.
International envoy Kofi Annan, whose peace plan brokered in April has not been implemented, warned against allowing "mass killings to become part of everyday reality in Syria."
"If things do not change, the future is likely to be one of brutal repression, massacres, sectarian violence, and even all-out civil war," Annan told the U.N. General Assembly in New York. "All Syrians will lose."
U.N. diplomats said Annan was proposing that world powers and key regional players, including Iran, come up with a new strategy to end the 15-month conflict.