US Secretary of State Mike Pompeo on Saturday described as “shameful” Russia and China blocking a UN Security Council resolution that would have extended for a year cross-border humanitarian aid to four million Syrian.

Pompeo said in a statement, “The Russian Federation’s and China’s veto yesterday of a Security Council resolution that allows for humanitarian aid to reach millions of Syrians is shameful”.

“To Russia and China, who have chosen to make a political statement by opposing this resolution, you have blood on your hands”, Pompeo added.

Humanitarian aid currently flows into Syria through UN-designated checkpoints in Turkey and Iraq without the formal permission of the regime in Damascus, but that authority is due to expire on January 10.

In October, Russain President Vladimir Putin spoke to his Turkish counterpart Recep Tayyip Erdogan over the phone and invited the Turkish leader to visit Russia soon.

The leaders also discussed the need to avoid possible conflicts between the Turkish and Syrian military, according to the statement.

Earlier, Turkey launched a cross-border assault on Kurdish fighters after the US decided to withdraw troops from Syria, a move that was criticised by the Republicans, with some terming it a “betrayal” of the Kurds.

The Syrian army entered the city of Tabqa in the northern countryside of Raqqa province, as part of its move to enter Kurdish-held areas to counter the ongoing Turkish assault in the region.

More than 50 people, including civilians, have been killed last week as the Turkish offensive in Syria, which was launched by President Recep Tayyip Erdogan aimed at pushing the Kurdish forces away from its border.

Russia, an ally and major supporter of Syrian President Bashar al-Assad, has used its veto 14 times on Syrian issues since civil war broke out there in 2011.

Syria has been the most intense battleground between the Islamist insurgents and the established state.

Russia never moved away from direct involvement in Syrian events, and the support he has provided to Syria over several years has played an important part in keeping the extremists at bay.