The carnage in Palmasola maximum-security prison outside the regional capital of Santa Cruz also left 60 people injured.

Defence Secretary Hagel said the U.S. will coordinate with the international community in deciding whether chemical attack was carried out.

Staff Sgt Robert Bales, 40, opened fire on men, children and women during the attack in Kandahar on 11 March 2012.

Troops and police had taken relatively low-key security measures before the "Friday of Martyrs" processions.

Oscar Isaac stars as a struggling folk musician navigating New York City's Greenwich Village folk scene in the Cannes Film Festival hit.

The follow-up to "Transformers: Dark of the Moon" - which grossed $1.12 billion at the global box office - features almost an entirely new cast.

The Vityaz, which is expected to replace the outdated S-300 systems, is superior to similar foreign models.

War in neighbouring Syria has raised sectarian tensions between the city's Sunni Muslim and Alawite communities.

Syria's government refutes the charge, while Syrian and Russian media have accused the rebels of staging the incident.

It was one of the worst attacks in Iraq since suicide bombers hit the same district two months ago, targeting a Shi'ite mosque.