At least 48 people killed in a string of bomb blasts across war-battered country

Top diplomats from the United States and Russia on Monday failed to reach a deal to ease fighting in Syria, US officials said, after government troops encircled rebel-held parts of Aleppo and a string of bomb blasts hit across the war-battered country.

However, US President Barack Obama and Russian President Vladimir Putin on Monday agreed on the sidelines of the G20 Summit in Hangzhou, Zhejiang province, to keep looking for a path to provide humanitarian relief to thousands of besieged civilians. The meeting was held as a series of bombings on Monday killed several dozen people.

The meeting, which lasted more than an hour, was "longer than planned", Kremlin spokesman Dmitry Peskov said.

A senior US State Department official said before the Obama-Putin meeting that a fresh round of crisis talks between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov on the margins of the G20 Summit had ended without agreement.

Washington and Moscow support opposing sides in the 5-year conflict, which has killed around 300,000 people and forced millions to flee.

A deal to provide aid to Aleppo's ravaged civilians and at least partially halt Russian and Syrian bombardments had looked likely on Sunday, before talks collapsed.

Syrian government troops renewed their siege of Aleppo on Sunday, with state media saying they had taken an area south of the city, severing the last opposition-held route into its eastern neighborhoods.

'Skepticism'

Once Syria's economic powerhouse, Aleppo has been ravaged by the war that began with protests against President Bashar al-Assad's government in March 2011.

The White House has been reluctant to tether Obama personally to a deal that could well fail.

Earlier truces in Syria have rapidly deteriorated and Obama warned on Sunday that the US was approaching the talks "with some skepticism".

But Obama said "it is worth trying".

"To the extent that there are children and women and innocent civilians who can get food and medical supplies and get some relief from the constant terror of bombings, that's worth the effort.," he said.

For Syrians, those efforts couldn't pay off soon enough as they not only face airstrikes but bombings that target civilians.

The blasts on Monday hit government-held Tartus and Homs, as well as Hasakeh, which is mostly controlled by Kurdish forces but where the government maintains a presence.

At least 48 people died in the multiple blasts, with dozens also wounded in a double bombing outside of Tartus city, which is a stronghold of the government.

"Two terrorist blasts on Arzuna bridge, the first a car bomb and the second a suicide bomber who detonated his explosive belt when people gathered to help the wounded," state television said.

There were no immediate claims of responsibility for the blasts.

But the Islamic State group??which is fighting both the government and the US-backed YPG militants??confirmed that one blast took place but did not say whether its fighters were involved.

AFP-AP-Xinhua