Tough negotiations between Iran and world powers over Tehran's nuclear program ended Thursday with a plan to meet next month for another round of talks but agreement on little else.

The open channels between Iran and the six-nation bloc -- the five permanent Security Council members plus Germany -- are seen as the most hopeful chances of outreach between Washington and Tehran in years. They also could push back threats of military action that have shaken oil markets and brought worries of triggering a wider Middle East conflict.

European Union foreign policy chief Catherine Ashton said both sides agreed to continue the discussions on June 18-19 in Moscow in hopes of a breakthrough on international concerns about the Islamic Republic's ability to build atomic weapons.

The announcement capped two days of negotiations in Baghdad, where at times it appeared Tehran would withdraw from the talks in frustration over the West's refusal so far to scale back tough economic sanctions.