Libya has began celebrating the first anniversary of the uprising against Muammar Gaddafi, with fireworks and slogans, even as its new leader vowed to act firmly against further instability.

The former rebels who, backed by NATO, toppled Gaddafi last year set up fresh check-points in the capital Tripoli, Benghazi, the eastern birthplace of the uprising, the western port city of Misrata and other towns.

Libya's new rulers have not organised any official celebrations at a national level as a mark of respect for the thousands of people killed in the bloody conflict that saw Gaddafi captured and slain on October 20.

But spontaneous commemorations began nationwide in cities and towns led by residents of Benghazi, the city which first rose against Gaddafi and his 42-year-old regime.

"I will fight with my body, heart and soul for our new Libya," said Mustafa Ahmed Ali, a young recruit of the new Libyan army as he ran in a procession with about 100 other comrades after passing a military training course in Benghazi on Thursday.

Men, women and children came out on the streets of Tripoli, Benghazi, Misrata and other towns to begin initial celebrations by setting off fire crackers and chanting slogans.

"Curly we are sorry!" shouted children dressed like angels in sarcastic reference to Kadhafi, who bore that nickname because of his distinctive locks, as they sat on top of cars in a procession in Benghazi that started from the landmark Tahreer (Liberation) Square.

Benghazi residents have organised a function later Friday to formally celebrate the anniversary, which is expected to be attended by Libya's new ruler Mustafa Abdel Jalil, interim Prime Minister Abdel Rahim al-Kib and other dignitaries.

Abdel Jalil warned that the revolutionary spirt of Libya and its stability will not be compromised in any way.

"We opened our arms to all Libyans, whether they supported the revolution or not. But this tolerance does not mean we are incapable of dealing with the stability of our country," he said in a television address late Thursday.

"We will be tough towards people who threaten our stability. The thuwar (revolutionaries) are ready to respond to any attack aimed at destabilising" the country, Abdel Jalil said.

Tripoli resident Naima Misrati said traffic police and former rebels were distributing leaflets, warning people against thinking of carrying out attacks, which said; "We cannot bring back the buried man (Kadhafi) but we can send you to him.".

Expressing her joy at the revolution, Misrata said she was celebrating "freedom for the first time."

"I have no words to describe my happiness. There is joy everywhere in Tripoli," she told AFP.

But one year after the uprising, Libya is battling challenges ranging from how to tame the rowdy militias that fought Kadhafi's forces to establishing a new rule of law in the country.

Thousands of people were killed or wounded in the conflict, the country's vital oil production ground to a halt, and homes, businesses, factories, schools and hospitals were devastated.

The challenges facing Libya's new rulers are manifold, including rebuilding an ageing and damaged infrastructure, fostering vibrant state institutions, tackling a corrupt economy and boosting what are weak health, judicial and educational systems.

But the most immediate headache is how to control the tens of thousands of ex-rebels who have now turned into powerful militias, whose jealously guarded commitment to their honour and power occasionally erupts into deadly clashes.

"By now they (militias) have developed vested interests they will be loath to relinquish," said World Bank advisor Hafed al-Ghwell in a recent report.

These rival militias have emerged as the biggest security threat for Libya, regularly clashing with each other and causing fatalities.

Global human rights organisations Amnesty International, Human Rights Watch and Doctors Without Borders have lashed out at them, accusing them of torturing their prisoners, most of whom are former pro-Gaddafi fighters.

"Armed militias operating across Libya commit widespread human rights abuses with impunity, fuelling insecurity and hindering the rebuilding of state institutions," Amnesty warned in a new report Thursday.

"It is imperative that the Libyan authorities firmly demonstrate their commitment to turning the page on decades of systematic violations by reining in the militias, investigating all past and present abuses and prosecuting those responsible," said Donatella Rovera, senior adviser at Amnesty.

Prime Minister Kib has acknowledged that integrating these militias into security services is a "complex" issue. But his government on Thursday said that about 5,000 of them had been integrated into the security services.

Ghwell said there are concerns about the ruling NTC itself.

"The NTC has had to struggle with internal divisions, a credibility deficit and questions surrounding its effectiveness," he said.