Turkey has begun building a "security wall" along part of its border with Iran, regional officials said Tuesday, in a move aimed at stopping Kurdish separatists.
Pictures showing huge concrete blocks being moved into place were published on the governor's website for the eastern Agri province.
Turkish authorities announced construction of a 144-kilometre (80-mile) long barrier in May as a means of blocking cross-border movements by members of the outlawed Kurdistan Workers Party (PKK). The entire Turkish-Iranian frontier is around 500 kilometres long.
The PKK, which has waged an insurgency inside Turkey since the 1980s, is considered by Ankara and its Western allies as a "terrorist" group.
On the diplomatic front, Turkey has been involved in co-sponsoring talks on a Syria peace deal held in Kazakhstan's capital with Iran and Russia.
To beef up security on its Syrian border, Turkey began constructing a similar wall two years ago to prevent Islamic State group fighters moving easily between the two countries and to clamp down on illegal crossings.
In June, Turkish Defence Minister Fikri Isik said 690 kilometres out of a planned 828 kilometres of the wall had been completed along the frontier with Syria.
He added that further border security measures would be put in place once the construction had been completed.