US Secretary of State John Kerry and his Russian counterpart Sergei Lavrov have agreed to extend a ceasefire agreement in Syria by 48 hours to allow for increased humanitarian access.

The truce, brokered by the United States and Russia, came into effect on Monday.

It is the second attempt this year by Washington and Moscow to bring an end to the five-year-long civil war.

State department spokesman Mark Toner said: "There was agreement that as a whole, despite sporadic reports of violence, the arrangement is holding, and violence is significantly lower.

"As part of the conversation they agreed to extend the cessation for another 48 hours."

Shortly before the truce started, violence was reported in several areas throughout the country.

Under the terms of the deal, if it lasts for a week, Russia and America will co-ordinate attacks against some rebel groups including Islamic State and al-Qaeda's former Syria branch known as the Nusra Front.