Afghan policemen stand guard near the site of a suicide attack in Kabul, Afghanistan January 10, 2017. [Photo/Agencies]

INSTABILITY IN CAPITAL AND BEYOND

The attack underlined the security threat posed by Islamist militants fighting to topple the Afghan government and drive out foreign troops stationed there for the last 15 years.

Afghan armed forces control no more than two thirds of national territory, and have struggled to contain the Taliban insurgency since the bulk of NATO soldiers withdrew at the end of 2014.

Several thousand, mainly Americans, remain in training and counter-terrorism roles.

The United States recently announced plans to send 300 Marines to the volatile southern province of Helmand, large parts of which are under Taliban control, as part of a regular rotation of troops helping train and advise Afghan forces.

Earlier on Tuesday, a suicide bomber killed seven people and wounded nine when he detonated his explosives in a house in Helmand used by an NDS unit.

Thousands of civilians have been killed in Afghanistan in the 15 years since the Taliban government was brought down in the U.S.-led campaign of 2001.

In July, the UN Assistance Mission in Afghanistan reported that 1,601 civilians had been killed in the first half of the year, a record since it began collating figures in 2009.

As well as the Taliban and associated groups including the Haqqani network, militants pledging loyalty to Islamic State have carried out major attacks in Kabul, most recently in November when more than 30 people were killed by a suicide bomber in a Shi'ite mosque.