BEIRUT — Syrian troops launched a broad ground assault Wednesday on rebel-held areas of the besieged city of Aleppo and activists reported clashes as opposition forces fought back in a battle that has raged for more than two weeks. And Amnesty International warned that new satellite images showed increased use of heavy weapons on residential areas. The group said images revealed at least 600 probable artillery impact craters alone in the nearby town of Anadan. Any attacks against civilians would be documented so that those responsible could be held accountable, it added. Activists said shellfire had killed at least 20 people in Aleppo Wednesday. Among the dead were a woman and her two children in the Al-Mashatiya district, the Syrian Observatory for Human Rights said. The UK-based group said at least 225 people were killed across the country on Tuesday, including 129 civilians, 50 rebels and 46 soldiers. Amnesty International said an image a week ago showed probable artillery impact craters next to what appeared to be a residential housing complex in Anadan. The official SANA news agency claimed regime forces have fully regained control of Salaheddine — the main rebel stronghold in Aleppo. It said the military inflicted heavy losses upon “armed terrorist groups,” the government's catchall term for its opponents. Meanwhile, President Bashar Al-Assad has vowed to crush the 17-month rebellion against him and to cleanse the country of “terrorists.” “The Syrian people and their government are determined to purge the country of terrorists and to fight the terrorists without respite,” he was quoted by SANA as telling visiting senior Iranian envoy Saeed Jalili. Assad appeared earlier on television for the first time in more than two weeks in his meeting with Jalili. Meanwhile, defected ex-premier Riad Hijab was in neighboring Jordan firming up his plans after his defection to the opposition, which Washington said showed the regime was crumbling. In that vein, Jordan's King Abdullah said Assad might make a “worst case scenario” retreat to an Alawite stronghold if he falls from power. Some experts have also predicted that if Damascus falls to rebels, Assad could take refuge among Alawites in the northeastern mountains of Syria, where opposition forces say he has already been stockpiling weapons. “I have a feeling that if he can't rule Greater Syria, then maybe an Alawi enclave is Plan B,” King Abdullah said in an interview with US television network CBS. On the humanitarian front, more than 22,000 Iraqis have fled Syria in less than three weeks, while 12,600 Syrians have done so since the beginning of the year, the UNHCR said. In Geneva, the World Health Organization said Syrians urgently need life-saving medicines, and the World Food Programme said 1.5 million people in rural areas would need food aid in the next three to six months. And Britain announced a grant of £10 million ($15.6 million) to aid thousands of Syrian refugees who have fled to Jordan, Lebanon, Turkey and Iraq. In Pretoria, US Secretary of State Hillary Clinton said that the world needs to decide how to end the conflict in Syria and start planning for a political transition in Damascus. “We must figure out how to hasten the day when bloodshed ends and the political transition begins,” she said after talks with her South African counterpart Maite Nkoana-Mashabane.— Agencies