Syrian rebels were fighting Wednesday to overtake a northern border crossing from government forces.

Rebels tore down the Syrian flag at the Tal Abyad post bordering Turkey after a day of fighting, but it was not clear if they controlled the entire crossing.

Fighters opposed to President Bashar al-Assad control several other crossings along the northern border with Turkey.

Meanwhile, rights group Amnesty International says there is evidence of what it calls an emerging pattern of indiscriminate attacks against civilians by the Syrian army.

Amnesty released a report Wednesday based on its investigation earlier this month in Idlib, Jabal al-Zawiya and north Hama. The group says government forces are routinely shelling towns and villages with imprecise weapons that should not be used in residential areas.

Amnesty International reiterated calls made by rights groups for the United Nations Security Council to refer the situation in Syria to the International Criminal Court for probes into possible war crimes.

It also warns that opposition fighters may also turn to indiscriminate attacks and is urging rebel groups to communicate to fighters that such violations will not be tolerated.

The report comes days after a United Nations panel presented a report blaming both sides for increasing the number of attacks against civilians.

The U.N. commission of inquiry says that although both government and anti-government forces committed war crimes, the abuses by opposition forces did not reach the “gravity, frequency and scale” of those carried out by pro-government fighters.

Also Wednesday, Iran's foreign minister was in Damascus for talks with Mr. Assad and other officials.