TRIPOLI/BENGHAZI, Libya - More than 40 people were killed on Thursday in an explosion at an army depot in southern Libya after locals tried to steal ammunition, officials said, while four soldiers died in clashes in the restive eastern part of the country.

The incidents highlighted the turmoil in Libya where the government is trying to restore order in the oil-producing country, which is awash with weapons after the 2011 ouster of Muammar Gadhafi.

The blast in Brak al-Chati, near the main southern city of Sabha, happened after a group of 43 locals and Africans went to the army depot to steal ammunition, a security official said.

"More than 40 people were killed," said Khalifa Alsghair, commander of a border security guard brigade in Brak al-Chati.

A local security official also put the toll at above 40 but medics in a hospital said the figure was probably too high because they had only received so far two dead bodies and four injured.

It was unclear what caused the explosion, which set off a fire.

Libya's nascent military is struggling to secure army bases and curb Islamist militants, militias and gangs who fought in the uprising against Gadhafi but refuse to disarm and control parts of the country.

The four soldiers were killed in Benghazi as clashes erupted between army special forces and militant Islamists of the Ansar al-Sharia group, officials said.

The trouble started when soldiers stopped a car loaded with weapons, explosives and large amount of money.

"Three soldiers were killed in clashes with Ansar al-Sharia," Wanis Bukhmada, commander of the special forces in Benghazi, said at a news conference.

He later told Reuters: "We will defend Benghazi."

Another soldier was killed by unknown gunmen in the morning in another part of the city, a security source said.

Fighting had initially started on Monday between army special forces and members of the Ansar Sharia in Benghazi, Libya's second-largest city. At least nine people were killed before the Islamists retreated from their main base. Three more soldiers were killed on Wednesday.

Appeal for dialogue

Army officials went on nationwide television on Thursday to appeal to the Islamists and other militias to lay down their weapons in Benghazi and start a dialogue.

"Brothers of the Ansar al-Sharia. You are Muslims and we are Muslims. We don't differ on religion ... but don't impose something which is not part of the religion," Salah Obeidi, army commander of the eastern region, said.

The security situation has sharply deteriorated in the past few months in Benghazi, where car bombings and assassinations are part of daily life.

Most countries have closed their consulates in the city of 1 million inhabitants, home to several oil companies. Some foreign airlines also have stopped flying there.

Ansar al-Sharia was blamed for the attack on the US consulate in Benghazi in September last year when the US ambassador and three other Americans were killed.

The chaos in Libya is worrying its neighbours and the Western powers that backed the uprising, which led to the fall of Gadhafi in one of the Arab Spring revolts.

Hoping to co-opt former fighters, the government hired militia groups to provide security. But they remain loyal to their commanders or tribes and often clash in disputes over territory or personal feuds.

Libya's oil exports are down to a fraction of capacity due to seizures of oilfields and ports by militias, tribesmen and civil servants demanding more political rights or higher pay.