Fierce battles between rebels and the army and police for control of the strategic city of Palma in northern Mozambique have left decapitated bodies littering the streets.
Thousands of people have disappeared in the city, which before the siege, which began last Wednesday, was home to around 70.000 people.
The Islamic State (IS) group claimed responsibility for the attack.
Rebels now control Palma's banks, government offices, factories and barracks, the IS claims, adding that more than 55 people have been killed, including members of the government army, Christians and foreign nationals.
Earlier this month, the United States declared the rebels in Mozambique a terrorist organization and announced that it had sent military experts to help train the Mozambican army to fight them.
The French oil and gas company Total announced last Sunday the continuation of work on the construction of the gas plant in Palma, an investment worth 20 billion dollars.
Fighting continued yesterday in the streets and in "pockets" across the city, Lionel Dick, director of the private military advisory agency Dick, which Mozambican police have hired to help fight the insurgents, told the AP.
The agency's helicopters were used to rescue captured civilians and fight insurgents.
About 220 people were rescued, including several wounded policemen.
The UN strongly condemned the attacks by jihadist groups and called them "heinous acts".
"We are deeply concerned by the situation that is still developing in Palma, where armed attacks began on March 24 that killed several dozen people," said UN spokesman Stefan Dižarik.
According to him, the UN continues to cooperate with the authorities on the ground in order to provide assistance to the vulnerable population.
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