BENGHAZI Libya (Reuters) - Libya's army urged residents to evacuate a central district of Benghazi that is home to its seaport, a spokesman said on Sunday, as it prepares a military operation against Islamists in the country's second-largest city.

At least 230 people have been killed since the army, backed by forces loyal to a former general, have waged an offensive against Islamist groups in the eastern city, part of chaos plaguing the oil producer three years after the ousting of Moammar Gadhafi.

The army has claimed to have seized back several barracks it had lost to the Islamists in August though fighting has been continuing in other parts of the eastern city.

"The chief of staff asks all residents of the Assabri district to leave by 12:00 noon (on Monday)," said Ahmed al-Mesmari, spokesman for the chief of staff.

The district is city's main commercial area and also home to the seaport used for wheat and petrol imports.

He gave no details but the army had previously said that members of the Ansar al-Sharia militant group had fled there after the army had seized other districts.

Separately, the Red Crescent evacuated the city's main childbirth hospital since doctors and nurses have struggled to come to work due to fighting close by, a spokesman said. The childbirth clinic, which will be moved to another hospital, got hit several times.

Six more people were killed on Sunday, lifting the death toll since the start of the army offensive to 230, medical authorities said.

The struggle is part of a wider conflict in the North African state where former rebels who helped oust Gaddafi are fighting for power and a share of the country's oil revenues.

Libya is divided between rival tribes and political factions with two governments vying for legitimacy since an armed group from the western city of Misrata seized Tripoli in August, forcing the internationally recognized Prime Minister Abdullah al-Thinni to move east.

The situation in Benghazi and other parts of Libya has been fluid with government forces unable to control militias.

Forces of former general Khalifa Haftar, which support the army in Benghazi, have planes from Libya's outdated air force though his opponents say he also gets air support from Egypt, which is worried about the spread of militants. Haftar denies this.