Opposition activists in Aleppo have accused Syria's government of bombing a busy market, killing dozens of people. Despite the crisis, Damascus says next month's election is likely to have 24 presidential candidates.
Three barrel bombs were dropped on market shoppers in Hillok, a rebel-held area of Syria's northern hub of Aleppo on Thursday, according to opposition activists.
The Britain-based Syrian Observatory for Human Rights put the death toll at 33. The local Aleppo Media Center said 44 people were killed. Medical facilities were overwhelmed with casualties.
Local activists said the bombs were dropped by a government helicopter. Fuel for electricity generators caught fire, extending the blaze. Previously, Hillok had been rarely hit in airstrikes during two years of battle by rebels and government forces for control of the city.
On Wednesday, an alleged airstrike by government forces on a school left dead 20 people, including 17 children.
The main Western-backed opposition group, the Syrian National Coalition, demanded after Thursday's attack that the "international community take immediate measures to protect civilians from airstrikes and neutralize the regime's aircraft."
Assad to run for third term
Despite the three-year-long civil war, Syria's state-run news agency SANA said 24 persons had applied for candidacy in next month's presidential election due on June 3. Thursday had been the deadline for applications.
The German news agency DPA said most candidates are relatively little known. Electoral laws had prevented exiles displaced by the war, including opposition figures, from running.
Syrian President Bashar al-Assad, who has announced his intention to run and win a third term, has in the past defied calls by the Syrian opposition and Western allies to step down in favor of a transitional government.
More fighting near Damascus
Activists on Thursday also said fighting on Wednesday night along a strategic route between Damascus and the border with Lebanon had resulted in at least 14 deaths.
Syria state news agency SANA said mortar fire on Thursday had killed a man and wounded two teachers in central Damascus.
Earlier in the week, a double car bombing in Homs and a mortar strike in Damascus killed at least 54 people.
Human Rights Watch said on Thursday that both of those attacks had targeted civilians.
It called on the UN Security Council to impose an arms embargo on any groups implicated in systematic human rights abuses.
ipj/ccp (AP, Reuters, dpa)