The International Committee of the Red Cross is moving some of its foreign staff out of the Syrian capital to neighbouring Lebanon.

A Red Cross spokesman in Geneva said the temporarily move was prompted by security concerns in Damascus but that a core team of about 50 staff would remain.

Hicham Hassan also said the Syrian Arab Red Crescent was suspending some of its operations in the northern city of Aleppo due to heavy fighting.

Mr Hassan said the Red Cross hopes to bring its staff back into the country in due course.

Meanwhile, the United Nations' leading human rights official expressed "deep alarm" at rising threats to civilians in Syria including a build-up of military forces that could preface a major showdown in Aleppo.

UN High Commissioner for Human Rights Navi Pillay said she is worried that a major confrontation in Syria's second-biggest city could be imminent.

She said her office fears for civilians' safety due to unconfirmed reports of atrocities, including extra-judicial killings and shooting of civilians by snipers during fighting in the suburbs of Damascus, and rising use of heavy weapons, tanks, attack helicopters and jet fighters in urban areas.

Ms Pillay said that "all this, taken along with the reported build-up of forces in and around Aleppo, bodes ill for the people of that city".