Syria's leading dissident said on Sunday US efforts to improve ties with Damascus could help democratic reform in his homeland.

Riad al-Turk, 79, told reporters in a rare interview that US President Barack Obama's initiative could also undermine what he called an "unconvincing alliance" between Syria and Iran.

Although arrests of opposition figures have continued despite US-Syrian diplomatic contacts, mending relations between the two countries would make it difficult for Damascus to crush dissent, Turk said.

"The rapprochement helps stabilize the Middle East and puts pressure on the Syrian regime to improve its policies," he said.

"It could be difficult for the regime to change its attitude toward Lebanon or Iraq and its role in the region without improving ties with its own society," he added.

Such improvements would help reform, said Turk, who spent around 18 years in solitary confinement as a political prisoner under the rule of President Bashar al-Assad's father, the late Hafez al-Assad.

"The regime would no longer be able to justify internal policy by talking about external dangers," said Turk.

The United States started talking to Syria shortly after Obama took office in January, departing from a policy of isolation under his predecessor, George W. Bush.

Bush imposed sanctions on Damascus for what Washington described as Syrian support for insurgents in Iraq, its role in Lebanon and backing for militant groups such as Hezbollah -- also backed by Iran.

The United States hopes that by talking to Syria and supporting efforts to resume peace talks between the Damascus government and Israel, Assad would break away from Iran.

OPPOSITION ALLIANCE

Undaunted by age, the scars of prison and six surgical operations, Turk remains the leading opponent of the Baath Party's monopoly on Syria's political system.

He has worked to spread democratic thought and maintain a broad opposition alliance known as the Damascus Declaration, after 12 of its younger members were arrested in late 2007 and sentenced to two-and-a-half years in jail each.

Senior US officials have visited Damascus twice this year since March, but the talks have not prevented Syrian authorities from pursuing a campaign of arrests against dissidents.

Turk said he was under no illusion that Syria's ruling elite might resist change, but ordinary Syrians also stand to benefit from a normalization of ties with Washington that helps revive Syria's battered economy and unhook the noose of sanctions.