Hanoi: Hundreds of black-clad mourners, weeping or lighting incense and laying wreaths, gathered early Wednesday for a somber final tribute at a state funeral for Vietnamese President Tran Dai Quang who died last week after a prolonged illness.

Long lines of officials, family, police and monks in golden robes streamed through the National Funeral House in downtown Hanoi where Quang's flag-draped coffin lay beneath a large portrait of the leader who passed away at age 61 on Friday.

His family sat vigil next to the coffin, dressed in black and wearing white headbands, and were greeted by stone-faced mourners, many who wept as they passed his body.

The country's top party cadres led tributes with large red, yellow and white floral wreaths, including Prime Minister Nguyen Xuan Phuc and Communist Party chief Nguyen Phu Trong, who lit incense and bowed their heads before the coffin.

A two-day national mourning period opened Wednesday.

Vietnam's communist leaders praised Quang's long devotion to the party, which he joined in 1980, and his more than four decades of service in the country's powerful security apparatus.

"He devoted his entire life and made numerous contributions to national revolutionary causes... his passing is a huge loss to our party, state and people," Deputy Prime Minister Truong Hoa Binh said at the prayer ceremony.

Quang courted a reputation as a hardline leader who was tough on dissent and drew criticism for overseeing a crackdown on activists and bloggers since he became president in 2016.

He also backed a sweeping anti-corruption campaign that has seen dozens of former and current officials and executives jailed in the past two years.

Though he was a member of the powerful politburo and was the country's head of the Ministry of Public Security for five years before he became president, his role as the official head-of-state was largely ceremonial.

Analysts have said his passing is not likely to shake up politics in the one-party state where the communist party maintains a tight grip on power.

Quang had sought medical treatment in Japan for more than a year before his death from a "rare virus", according to officials, who did not provide further details.

He had appeared thin and wan in recent weeks, though he continued to work right to the end of his life, appearing in public two days before his death.

"I don't understand why he had been working until almost the very last day... If he was an ordinary person, he would have a chance to rest and enjoy his last minutes," a local resident, who gave the name Nga, told AFP outside the funeral house.

Quang will be buried in his hometown in Ninh Binh province on Thursday, closing two days of national mourning during which entertainment venues will be shut.