But a statement from the office of the UN co-ordinator for Afghanistan on Monday said that new sanctions would increase the risk to the UN on the ground and "hinder the ability of aid agencies to provide life-saving support."
A further three staff members left the capital, Kabul, on Tuesday, heading for neighbouring Pakistan.
This brings to eight the number of UN personnel who have left in the past three days following security concerns, though around 100 international staff still remain.
Last week, Washington and Moscow indicated that they will ask the Security Council to impose tighter sanctions on the Taleban rulers, leading to fears of reprisals against UN expatriates.
In November last year, relief agencies were force to evacuate when violent protests erupted after limited sanctions were imposed.
A UN aid worker told BBC News Online she expected a larger pull-out by the end of the week as a security precaution.
Relief work 'at risk'
A UN spokeswoman, Stephanie Bunker told the French news agency, AFP that UN operations were continuing normally.
But a statement from the office of the UN co-ordinator for Afghanistan on Monday said that new sanctions would increase the risk to the UN on the ground and "hinder the ability of aid agencies to provide life-saving support."
One UN aid worker, who asked to remain anonymous, told BBC News Online the atmosphere in Afghanistan on Tuesday remained, "totally normal".
She said the Taleban distinguishes between the political and humanitarian sides of the United Nations and UN humanitarian aid is too important for the Taleban to "throw the UN out".
But she said the Taleban had warned that "people would be angry" - suggesting they will organise demonstrations if any new sanctions are imposed.
She said the aid community was "disappointed by the one-sidedness of the sanctions" and added there would be a very serious risk to all internationals in Afghanistan if the US decided to launch strikes against the country, as it did in 1998.
Sanctions would prolong the conflict and so worsen the situation of people already devastated by war and drought, she said.
Taleban 'responsible'
The US State Department said on Tuesday that the sanctions were designed to only target the Taleban leadership, not relief operations.
"We will hold the Taleban responsible for any negative developments on the humanitarian front," it said.
The United States hopes sanctions will force the Taleban to hand over Osama bin Laden, whom they accuse of the bombings of two embassies in east Africa in 1998.
Russia thinks bin Laden has also had a hand in helping Islamic militants in Chechnya and elsewhere in the former Soviet Union.
But the Taleban says it has received no evidence implicating him in the embassy bombings and refuses to release him.