HERAT: Nato troops on Thursday made Afghan security forces responsible for the city of Herat.

Herat is the fourth of seven areas to transition to Afghan control this week, but critics say the timetable is politically motivated and not reflective of Afghan abilities to ward off the Taliban with violence at a 10-year high.

Underscoring the threat, a suicide bomber killed four people on Wednesday in the north's Mazar-i-Sharif, considered one of the safest cities in Afghanistan and due to be transferred on Saturday.

In Herat, a ceremony took place at Nato's International Security Assistance Force headquarters in the city, attended by the defence minister, other senior Afghan officials and Italy's economic development minister Paolo Romani.

Italy is in charge of coalition efforts in Herat.

“We don't want a parallel security force. The ANA (army), ANP (police) and our intelligence forces are prepared to defend our country and crush the enemy,” said Ashraf Ghani, head of the national transition authority.

A separate ceremony was later held at an Afghan army base in the city.

Transition comes with US and Afghan officials trying to reach out to the Taliban to broker a peace deal as Nato-led troops begin a gradual withdrawal designed to recall all foreign combat troops by the end of 2014.

But the speed of the drawdown and transition has been criticised by experts who say Afghan forces are not ready to take control for security on their own.

An MP for Herat and deputy speaker for parliament, Ahmad Behzad, said that the city, which lies close to the Iranian border, is largely safe but is still plagued by unrest nearby in the province, in particularly in Shindand district.

“Herat city and the province is under threat by these places,” said Behzad.

Foreign forces have been absent from the city for some time he said, but Afghan troops are still heavily reliant on the Nato presence for air support and other military equipment.