The United Nations officials in Afghanistan expressed concerns regarding growing violence and threats against aid workers in Afghanistan, as the country is going through difficult security transition.

United Nations Humanitarian Coordinator in Afghanistan, Mark Bowden said Saturday that United Nations remains extremely concerned with the trend which comes amid difficult transition in the country that could lead to increased humanitarian needs.

UN has called the security threat against the foreign aid workers and their Afghan colleagues working on development and reconstruction prjects as worrying.

The comments by Mark Bowden were followed after unknown gunmen killed nine aid workers in northern and southern Afghanistan, including six aid workers belonging to a French non-governmental organization.

At least 73 aid workers have been killed, kidnapped or injured in various incidents across Afghanistan since the beginning of 2013, according to Aid Worker Security Database.

In the meantime, the United Nations in its statement said at least 36 aid workers have been killed in Afghanistan so far this year.

The United Nations also expressed concerns regarding the growing casualties of the Afghan civilians and Afghan national security forces, as the NATO-led coalition security forces are preparing to withdraw from the country by the end of next year.