Damascus (AFP) - Syrian President Bashar al-Assad congratulated key ally Iran Tuesday on reaching a nuclear deal with world powers, calling the agreement a "great victory".

In a message to supreme leader Ayatollah Ali Khamenei, Assad said he was "happy that the Islamic Republic of Iran has achieved a great victory by reaching an agreement", state news agency SANA reported.

"In the name of the Syrian people, I congratulate you and the people of Iran on this historic achievement," he added in another message addressed to President Hassan Rouhani.

Assad said the deal would be a "major turning point in the history of Iran, the region and the world."

He added that it provided "clear recognition on the part of world powers of the peaceful nature of Iran's nuclear programme, while preserving the national rights of your people and confirming the sovereignty of the Islamic Republic of Iran."

"We are confident Iran will continue, and with greater momentum, to support the peoples' just issues and to work towards establishing peace and stability in the region and the world," Assad said.

Syria's foreign ministry also welcomed the deal, which it said underlined "the importance of adopting diplomacy and political solutions to resolve international disagreements."

Tehran is a longstanding ally of Damascus and has remained so since Syria's uprising began in March 2011.

It has bolstered Assad's government with military and financial support, including a $1 billion (900 million euro) credit line approved by Syria's parliament on July 7.

It is also a key ally of Lebanon's Hezbollah movement, which has dispatched fighters to help Assad's forces battle the uprising.

More than 230,000 people have been killed in Syria since the conflict began with anti-government demonstrations more than four years ago.