By Alexander Dziadosz and William Maclean
TRIPOLI (Reuters) - Libya's interim government chief, Mustafa Abdel Jalil, made his first speech to a crowd of about 10,000 in the capital Tripoli on Monday -- a sign of growing confidence from the former rebels.
Abdel Jalil arrived in Tripoli on Saturday for the first time since his allies chased Muammar Gaddafi out of the city, a move that political analysts saw as key to his credibility.
The chairman of the ruling National Transitional Council called on the movement's fighters not to engage in reprisal attacks against remnants of the Gaddafi government.
Repeating a call made before, he also said that Islamic sharia law should be the new Libya's main source for legislation.
"We need to open the courts to anyone who harmed the Libyan people in any way. The judicial system will decide," he told the crowd, calling for no attacks on former Gaddafi allies.
"We seek a state of law, prosperity and one where sharia is the main source for legislation, and this requires many things and conditions," he said, adding that "extremist ideology" would not be tolerated.
Abdel Jalil had been running the provisional administration from the eastern city of Benghazi, cradle of the revolt that overthrew Gaddafi in late August.
NTC officials told Reuters they did not advertise the public appearance for fear pro-Gaddafi elements would try to disrupt it.
The crowd cheered, waved the independence tricolour flag. Balloons, fireworks, music and the smell of popcorn gave the gathering a carnival atmosphere.
"The most important thing was what he said about building a nation of laws, and his reassurances about extremism, from the left or the right, Islamists or secularists," Osama Gheriani, a 30-year-old dentist, told Reuters. "It's a moderate country. This was the most important point."
Some of the hesitation in Abdel Jalil's arrival in Tripoli after the fall of Gaddafi seemed to stem from long-standing regional rivalries and from a sense that Tripoli -- run by rebel brigades that swept in from towns and provinces eager for a share of power -- may not be a safe place for every official.
The NTC's timetable which sets out plans for a new constitution and elections over a 20-month period, should start once the NTC declares Libya's "liberation."
It has yet to do so and it is unclear exactly how the disparate groups which have taken over the country will define what constitutes "liberation."
Several parts of the country's south and three major towns -- Bani Walid, Sirte and Sabha -- are still controlled by forces loyal to Gaddafi.
"Bani Walid, Sirte and Sabha are now under siege by Gaddafi forces. We are betting that our brothers in those cities will fulfil their expectations and you will see them do so soon," Abdel Jalil said.
(Additional reporting by Joseph Nasr in Berlin; writing by Barry Malone; editing by Philippa Fletcher)
