The United Nations has accepted Syria's invitation to investigate the alleged use of chemical weapons in the ongoing Syrian conflict. This offer comes amid  growing tensions between Moscow and Washington over the use of these weapons.

The Obama administration last month offered direct military aid to Syrian rebels saying the government under the regime of President Assad had crossed the "red line" by using chemical weapons against the rebels who were struggling to over throw the regime.

The United Nations disarmament chief and the head of the team probing the alleged use of chemical weapons have accepted the invitation to visit Damascus in a bid to do a proper, efficient, safe and successful investigation. The White House had earlier urged the Syrian government to allow the U.N. team to investigate independently.

"If (Syrian President) Bashar al-Assad is seriously interested in proving his assertion, and now the assertion that Russia is making, Assad should let the UN investigators in and Russia should use its relationship with Assad to press Assad to allow UN investigators in," said the  White House spokesman Jay Carney.

Russia earlier had strongly objected to Washington's decision to arm the Syrian rebels and counter-claimed that rebels in Syria had used chemical weapons against the government military.

Since the civil war broke out in March 2011, as many as 100,000 people have been killed and almost two million Syrians have been forced to take refuge in neighboring countries.