UN Secretary-General Ban Ki-moon Sunday called on the Libyan authorities and factions in the Libyan city of Bani Walid to resolve the stand-off peacefully.

In a statement released by his spokesperson's office, Ban said he is alarmed by the fighting in and around of Bani Walid, and in particular the reports indicating growing civilian casualties due to indiscriminate shelling.

Ban reminded all parties of their obligations under international humanitarian law and called on the Libyan authorities and those in Bani Walid to begin immediately a process to resolve the stand-off peacefully, said the statement.

Bani Walid has been under siege for more than 18 days by forces from different factions, which demanded the handover of a number of people accused of kidnapping and torturing Omar ben Shaaban, who reportedly captured former Libyan leader Muammar Gaddafi.

"The Libyan authorities must be able to extend Libyan sovereignty and state control and services throughout the territory of Libya," Ban said in the statement, urging all Libyans to work together to strengthen the legitimacy and effectiveness of state institutions across the country.

"The state and those militias acting in its name also have a responsibility to the people of Libya to act fully in accordance with international law, in particular international human rights law," he said.

The UN chief believed the situation in Bani Walid can be resolved in a peaceful manner that preserves the rights of all Libyan citizens and permits the authorities to exercise its responsibilities there.