By AP / 12 Apr 2013

The Syrian regime has carried out indiscriminate and sometimes deliberate air strikes against civilians that have killed more than 4,300 people since last summer, an international human-rights group said yesterday.

Human Rights Watch (HRW) said Syrian fighter jets had deliberately targeted bakeries, breadlines and hospitals in the country's north.

Parts of the north - especially areas along the border with Turkey - have fallen under the control of rebels fighting to topple the president, Bashar Al Assad, including several neighbourhoods in Aleppo, the country's largest city.

"The aim of the air strikes appears to be to terrorise civilians ... particularly in the opposition-controlled areas where they would otherwise be fairly safe from any effects of fighting,"said Ole Solvang of HRW, which is based in New York.

These attacks were "serious violations of international humanitarian law", and the people who commited such breaches were "responsible for war crimes", the group said in a report released yesterday.

Mr Solvang had led a HRW team that inspected 52 sites in northern Syria and documented 59 unlawful attacks by the Syrian air force. At least 152 people were killed in these attacks, according to the report.

In most of the strikes, the regime planes had appeared to have no military target - such as armed opposition supporters or rebel headquarters - in sight when they dropped their weapons on civilian areas, the group said.

The 80-page report concluded that across Syria, more than 4,300 civilians had been killed in attacks by regime jets since last July.

It is the most comprehensive study of Syrian air-force operations since last summer, when Mr Al Assad's forces began to rely heavily on fighter jets to repel rebel advances and reverse their territorial gains.

Officials in Damascus could not immediately be reached for comment on the report.

Opposition fighters now control large swathes of northern Syria, and last month captured their first provincial capital, the city of Raqqa. They also hold entire districts of Aleppo, and some key infrastructure in the east, including oil fields and dams on the Euphrates River.

With the recent influx of better weapons and other foreign aid, the rebels have also made major gains in the south, seizing military bases and towns in the strategically important region between Damascus and the border with Jordan, about 160 kilometres from the capital.

The rebels hope to eventually storm Damascus from the south.

While they have made major gains, they often cannot hold on to the territory because of the regime's superior air power.

The continued threat from above has also stalled efforts to govern rebel-held areas effectively, allowing opposition leaders from the western-backed Syrian National Coalition only brief excursions into areas under rebel control. HRW noted that air force jets had increasingly been hitting targets around Syria, including in the capital, Damascus, and in Raqqa. The air raids in the rebel-held northern areas occured daily, the group said.

The air-strike campaign appears to be aimed at preventing the opposition from running areas captured from the regime.

"The air force has no other reason to continue hitting rebel areas but to prove to the opposition that it can't rule,"Mr Solvang said.

For its part, the opposition alliance has been marred by severe divisions in its ranks since its formation late last year in Qatar, and its leaders are mostly seen as disconnected from the myriad rebel forces fighting inside Syria.

The US secretary of state, John Kerry, met opposition leaders in London on Wednesday to discuss ways to step up aid to the rebels.

The United Nations estimates that more than 70,000 people have been killed in the two-year conflict.

It started with peaceful protests against Mr Al Assad's rule, inspired by other Arab Spring uprisings, but descended into civil war following a harsh regime crackdown.