Damascus: Syrian troops killed 12 civilians on Wednesday, five of whom were attending a funeral in Damascus and were caught up in the regime's continuing crackdown on dissent, a human rights group said.

Starting at dawn, when the crackle of gunfire could be heard sustained for half an hour, the death toll steadily rose through the day.

The Syrian Observatory for Human Rights said: "Six civilians were killed in the Damascus neighborhood of Barzeh, five of whom were slain by security forces who fired on the funeral of a young man.

"Three other civilians perished under the bullet of the regime's forces at Inkhel, in the southern Daraa region, and seven protesters were wounded in the neighboring locality of Jassem who were protesting against the repression," it added.

The continuing killing -- which on Tuesday resulted in another 20 bodies -- has increased international anger at Syria which only last week signed up to an Arab League peace plan which called for an end to violence.

Under the plan, Damascus would also release those detained for protesting, and withdraw all Syrian forces from towns and cities. It says it has already released more than 500.

But since signing the Arab roadmap, up to Tuesday according to the United Nations, Syrian forces have killed another 60 people, adding to the UN estimate of 3,500 who have died in the crackdown on protests which erupted in mid-March.

The opposition Syrian National Council -- an umbrella body grouping most of the pro-democracy currents -- has urged the Arab League "to take a strong and effective position against the Syrian regime commensurate with the dangerous development of the situation in Syria, especially in... Homs."

It wants the League to freeze Syria's membership, impose economic and diplomatic sanctions, and seek the referral of allegations of genocide and other human rights violations by the regime to the International Criminal Court.

Listing the latest dead, the Britain-based Observatory said two more civilians were shot and killed in Homs -- the besieged flashpoint city 160 kilometers (100 miles) north of Damascus -- and one civilian in Abu Kamal in the east, killed during checks and questioning by security forces.

Three people, one of them a child, died under the bullets of the regime's forces in the southern region of Daraa, birthplace of the eight-month-old protest movement against President Bashar al-Assad, the Observatory said in a statement.

In Brussels, diplomats said the European Union is readying a freeze on European Investment Bank credits to Syria as it mulls more sanctions on Assad's regime, with a decision expected at a meeting of foreign ministers next Monday.

British Foreign Secretary William Hague joined those demanding the Arab League respond promptly to Syria's failure to abide by its commitments.

"I call on the Arab League to respond swiftly and decisively to the Syrian regime's failure to implement the agreement so far," said Hague. "The international community looks to these Arab nations to show decisive leadership to address this crisis in their midst."

Ravina Shamdasani, spokeswoman for the UN High Commissioner for Human Rights, described the situation in the embattled neighborhood of Homs as "appalling," with residents deprived of food, water and medical supplies for the past week.

NATO, which intervened in Libya, has ruled out operations in Syria, and UN Security Council sanctions are unlikely because Russia and China, both with the power of veto, are allies of the Assad regime.

This has put the Arab League in the spotlight as the best possible chance of bringing pressure on Damascus.

The Cairo-based League is due to hold an emergency ministerial meeting on Syria next Saturday.

Syria meanwhile has apologized to Lebanon over repeated border violations and has vowed to respect its neighbor's independence and sovereignty, Lebanese President Michel Sleiman's office told AFP. A number of Syrian opposition figures have disappeared in Lebanon.