The rebel National Transitional Council in Libya officially declared the country free of the regime of longtime leader Muammar Gaddafi 3 days after his killing Thursday.

Tens of thousands gathered in jubilation at the central square in capital Tripoli for the ceremony.

Gaddafi was killed Thursday in after a skirmish with rebel forces in his birth town of Sirte, where he was hiding.

His autopsy confirms that the former Libyan leader has received multiple gun wounds, including one in the head.

NATO plans to end its operation in support of the anti-Gaddafi rebels in a week, on October 31.

Gaddafi, 69, ruled Libya with an iron fist for almost 42 years. The demise of his regime came after a nine-month civil war struggle. Libya's long-serving strongman  was toppled by a popular uprising on August 22, 2011

Late on Saturday, Saif al-Islam, the late Libyan dictator's most powerful son, vowed to take revenge for his father's death.

"We are continuing resistance. I am in Libya, I am alive and free and willing to fight to the end and take revenge," Saif al-Islam declared in an alleged statement aired by Syria-based Alrai TV channel.

Earlier, a website of Gaddafi's supporters  posted a statement that Seif al-Islam had been named an heir to the Libyan strongman and is now in and charge of the forces fighting the Transitional National Council.