Three Nato soldiers have been killed in an attack by insurgents in the east of Afghanistan, officials say.

The three were part of the Nato-led International Security Assistance Force (Isaf).

The incident happened in the province of Paktia, which borders Pakistan.

More than 100 foreign soldiers have been killed in Afghanistan this year - nearly 80 of them Americans. Isaf currently has troops from 50 nations, most of them from the US.

By the end of 2014 all foreign combat troops are due to have left Afghanistan to be replaced - if approved by the Afghan government - by a smaller force that will only train and advise.

US President Barack Obama has not yet said how many troops he will leave in Afghanistan along with other Nato forces at the end of 2014.