A suicide bomber killed on Monday a top Yemeni army general who was leading the fight against Al-Qaeda in the country's restive south, medical and military officials told agencies.

General Salem Ali Qoton, southern Yemeni army commander, was killed in the port city of Aden while on his way to office in an attack seen as a blow to Yemen's fight against the militant group.

"General Qoton was killed and four others were wounded in a suicide attack," near his home in the Mansoura neighbourhood of Aden, the medic said on condition of anonymity.

The medic, who is also a relative of Qoton, said the attacker 'handed Qoton a paper, shook his hand and then detonated himself,' when the general was walking to his office.

As the chief military commander in south Yemen, Qoton had led a month-long offensive against Al-Qaeda, forcing the militant group to withdraw from several towns and villages in the restive Abyan and Shabwa provinces which they had controlled since last year.

The Monday morning attack came as Al-Qaeda fled from their last bastion in the town of Azzan in Shabwa.

Since last week, Al-Qaeda has withdrawn from three other strongholds in Abyan, including the capital Zinjibar, and the towns of Jaar and Shuqra.

Qoton was appointed in March just days after newly elected President Abdrabuh Mansur Hadi took office and pledged to destroy Al-Qaeda in the Arabian Peninsula, the name given to the militant group's local Yemen branch.

The post had been held for decades by General Mahdi Maqola, known for his close ties to former president Ali Abdullah Saleh.

Saleh was accused by his opponents of allowing Al-Qaeda to establish a stronghold in Yemen's mostly lawless south and east.

Qoton's appointment was in line with the Gulf sponsored power-transition deal that saw Saleh quit after 33 years in power, and required Hadi to restructure the Yemeni army during a two-year interim period.

Ali Mansur, a senior army commander and close aide to Qoton described the general's death as 'a huge loss for Yemen and its efforts to fight Al-Qaeda'.

Speaking to AFP by phone, Mansur said the attack 'bears the hallmark of Al-Qaeda,' though the militant group have not formally claimed responsibility for his death.

He gave Qoton full credit for the recent Yemen army's victories against Al-Qaeda in both Abyan and Shabwa.

'In just three months, Qoton achieved major progress towards chasing down and eliminating' the militants from their strongholds, said Mansur.

Azzan's deputy mayor said on Monday that Al-Qaeda completely withdrew from the town, the last bastion in Yemen where the militants had full control.

Yaslam Bajanoub said that the jihadists 'handed over the city late Sunday night to a committee of tribal mediators'.

Al-Qaeda had declared an Islamic emirate in the desert town where hundreds of fighters are believed to have sought refuge after fleeing their strongholds in Abyan which fell to army control this past week.

Bajanoub said the jihadists also fled the neighbouring village of Al-Huta.

On May 12, the Yemeni army began its offensive to recapture territory lost to the militants.

A total of 567 people have died in the campaign -- 429 Al-Qaeda militants, 78 soldiers, 26 militiamen and 34 civilians -- according to an AFP tally compiled from various sources.