Herat, Afghanistan - Surrounded by tight security, German Foreign Minister Frank-Walter Steinmeier arrived Friday in Afghanistan for a surprise visit.

Steinmeier, who is expected to stay several days in the country, arrived Friday morning in the western Afghanistan city of Herat in a German military plane.

It is Steinmeier's third visit to Afghanistan.

Germany currently has 3,500 troops stationed in the war-torn country and is under pressure from NATO allies to increase the presence by 1,000 soldiers by this autumn.

In October Germany's parliament will decide on whether or not to extend the mandate for the mission to Afghanistan.

Herat, a city with 600,000 inhabitants and Afghanistan's third largest city is regarded the country's cultural centre.

Steinmeier is to be briefed on rebuilding Herat's drinking water supply system, which is financed by Germany, and several cultural projects.

Further details of his schedule were not released due to security reasons. (dpa)