Just ahead of US President Barack Obama's historic visit to Vietnam on Sunday, the communist nation released from prison a prominent Catholic dissident.

Rev. Nguyen Van Ly was lean but in good spirits, the Catholic Archdiocese of Hue said on Saturday, a day after his release. Ly has suffered from health issues.

The priest was released three months before his eight-year sentence was due to be up - a symbolic move ahead of Obama's state visit in which the president has been called on to address human rights.

Ly has been in and out of prison for decades for advocating political and religious freedoms in the communist nation, where dissent is often met with harassment and arrest.

The United States and Vietnam have developed a budding relationship in recent years, a historic development between two countries that once fought a bitter war.

A resurgent China and disputes over the South China Sea have brought the United States and Vietnam closer together, as have the prospects of expanding trade and investment.

Obama's visit is a part of his administration's so-called "pivot to Asia," a reshuffling of US military, political and economic resources towards the Asia Pacific.

Vietnam, for its part, hopes the United States will lift an arms embargo. Human rights groups and members of the US Congress opposed to lifting the arms embargo point to Vietnam's dire human rights record.

Obama will spend three days in Vietnam before heading to Japan for a G-7 summit.

cw/bw (AP, dpa, Reuters)