Iran says it will start the principal phase of military exercises near the Afghan border next week.

Two-hundred-thousand troops are said to be involved, along with the air force and navy.

The manoeuvres were due to start last month, but were postponed while a United Nations special envoy, Lakhdar Brahimi, toured the region trying to negotiate a peace process in Afghanistan.

Tension between Iran and the Taleban authorities in Afghanistan rose sharply in August after eight Iranian diplomats and a journalist were killed during a Taleban offensive on the Afghan city of Mazar-i-Sharif