Nuclear watchdog investigating suspected atomic bomb research by Iran.

Time running out for Syria to hand over chemical weapons stocks.

Supreme leader said Iran had agreed to the talks to "break the hostile atmosphere."

Negotiators struggled to narrow gaps in talks aimed at reaching accord.

Officials hope to settle dispute over Tehran's nuke program by late July.

Experts from Iran and six world powers are aiming to reach a resolution on the thorny issue by July.

Calls nomination of a former hostage-taker as ambassador to U.N. "extremely troubling."

Rights group found a jump of almost 15% compared with 2012.

Will reconvene in April; all sides hopeful of June agreement.

Both camps remain optimistic over the chances of reaching a permanent deal before July.