US Defence Secretary Ash Carter has announced that it will increase support for on-going counter-terrorism and force-protection missions in Afghanistan.

The country’s troops will support Afghan air and ground forces by providing advice and firepower, including close air support.

US President Barack Obama has agreed to grant increased flexibility to US forces in Afghanistan this year, based on recommendations made by Carter and US Marine Corps general Joe Dunford.

"The US will continue to lead the NATO effort in southern and eastern Afghanistan."

Carter said: "This supports our on-going counterterrorism and force-protection missions there (and) Nato’s Resolute Support mission, because a more capable Afghan force only makes our (deployed) forces … more secure, and it will help the Afghans … as we prepare for the US and Nato missions in 2017."

The Afghan National Defence and Security Forces will get full funding from the US until the end of this decade.

The US also plans to reduce the number of troops in Afghanistan from 9,800 to 5,500 by the end of 2016.

Carter added: "The US will continue to lead the Nato effort in southern and eastern Afghanistan, and we will continue to provide coalition partners with sufficient enabling capabilities needed for their own presence, particularly in northern and western Afghanistan."

Nato counterparts also are planning to provide funding for the Afghan national security forces through 2020.