Turkey called Friday for rapid international action to supply humanitarian assistance to besieged cities in Syria but said the time was not right to begin arming the Syrian opposition.

“We are talking about what should be done today,” said Turkish Foreign Minister Ahmet Davutoglu, in Washington for consultations with the Obama administration. His visit is part of an international effort to organize an effective response to the Syrian carnage after the veto of a United Nations resolution last week calling on Syrian President Bashar al-Assad to step aside.

As if to underscore the urgency, two massive explosions reportedly killed at least 25 people in the northern Syrian city of Aleppo Friday, while Assad’s military continued its week-long shelling of civilian residents barricaded inside the city of Homs.

No one claimed responsibility for the bombs, which Syrian television blamed on what the government says are foreign-backed “terrorists.” Both blasts struck government security compounds.

The explosions were the first major violence in a city where the 11-month uprising against Assad has yet to take hold. Mohammed Abu-Nasr, an Aleppo-based activist, said the blasts came on a day when activists were planning wide protests in the city after Friday prayers, the Associated Press reported.

Davutoglu, who is due to meet with Secretary of State Hillary Rodham Clinton Monday, said that a fifth of the Syrian Army, up to 40,000 troops, has now defected to the opposition. Many have crossed the border into Turkey, where senior military defectors say they are directing the internal resistance, but Davutoglu said his government is not providing any military support.

Assad, he said, is “now fighting against his own people. This cannot be tolerated. We cannot wait and see like Sarajevo,” the Bosnian capital where Serbian forces rained artillery on civilians while the international community hesitated to intervene.

Davutoglu said that discussions were continuing on the details of how humanitarian supplies could be delivered to cities he said were suffering from a lack of food and medical goods without armed protection. “When I say access, it doesn’t always have to be a land corridor,” he said, suggesting that the answer might be initiatives by the International Red Cross or its partner Red Crescent organization.

He echoed the administration and other governments in saying that discussion of any international military backing for the opposition or direct intervention was premature. “We need a new initiative, a new international platform, to raise concerns” about the “massacres” of civilians, Davutoglu told a group of reporters.

Davutoglu said that 120 people had been killed by government shelling this week in Homs, and “that’s why there are all these consultations.” The United Nations stopped tallying the overall death toll in the Syrian uprising in January, when it reached 5,400, saying the numbers were too difficult to accurately compile.

In addition to Davutoglu’s travels, Jeffery D. Feltman, the U.S. assistant secretary of state for Near East affairs, has been traveling through the Middle East and North Africa to solicit views. The end result is likely to be an international conference similar to the “Friends of Libya” effort that preceded NATO and Arab military intervention in that country.

NATO has said repeatedly that it has no intention of intervening in Syria. But the precedent of large-scale international consultation is seen as a useful one to demonstrate to Assad that his number of friends is dwindling.

U.S. and Turkish officials said that a “Friends of Syria” gathering could be held as early as next week, following a Sunday meeting of the Arab League in Cairo. As they were in Libya, Western governments have been eager to allow Arabs to take the lead in formulating a response to the Syrian crisis.

Last month, an Arab League initiative failed when Arab monitors on the ground in Syria were unable to stop government attacks on civilian protesters, and efforts to persuade Assad to allow a government transition were similarly unsuccessful.

The Arab League then turned to the U.N. Security Council. Russia, along with China, vetoed the Arab-sponsored resolution, and Russian Foreign Minister Sergey Lavrov traveled to Damascus to meet with Assad.

Lavrov said he obtained a pledge to stop the violence, just as the shelling on Homs began.

“We told Russia that the same promises were given to us five times last year” during visits to Assad, Davutoglu said. “We hope Russia will make a new assessment” of cooperation with the international community, he said.